Bonn — If Christian Democrat Helmut Kohl succeeds in his plans and takes the oath of office in early October, he will be the youngest, and possibly the tallest, chancellor in West German history.
He will also be the first to hail from the provinces and one of the first not to speak English.
He will come with a reputation as a ''man of integrity'' (according to one civil servant), an ''amiable person'' (another civil servant) but one who ''gives in to pressure'' (a member of Parliament), a party leader who skillfully ''saved the unity'' of the conservatives (a Christian Democrat activist) but a man who ''lacks self-confidence'' (a European diplomat).
''He's a nice guy. But that's not enough to be chancellor of the Federal Republic of Germany,'' commented a Social Democrat MP. His remark summed up the notable lack of enthusiasm in Bonn for an impressive votegetter, who in 1976 won a 48.6 percent plurality, or even more than the popular Helmut Schmidt (who was reelected chancellor only by the combined votes of the left-Liberal coalition).
(The Free Democratic Party endorsed Sept. 28 a pact with Dr. Kohl's party to oust Chancellor Schmidt on Oct. 1.)
This ''nice guy'' represents a new generation in West German politics. He was 15 when World War II ended and was not even conscripted into the desperate schoolboy antiaircraft batteries of the last months.
By contrast, Mr. Schmidt was a young lieutenant in the war. The previous chancellor, Willy Brandt, had left Germany as a convinced young Social Democrat to join the anti-Hitler movement abroad. Chancellor Kurt Georg Kiesinger had been a Nazi party member. Founding father Konrad Adenauer, already a senior politician as mayor of Cologne, had stayed in Germany but refused to collaborate with the Nazis. All were strongly marked by their adult World War II experience.
In keeping with his age Dr. Kohl has sometimes made a special appeal to German youths to join his Christian Democratic Union (CDU) in making ''a new beginning.'' He is not really perceived as a fresh face, however, and he has had little response to his summons. Among all ages he lags behind Schmidt in personal opinion polls, and the failure of the CDU as a whole to attract more young people is periodically lamented by the party.
Even with a natural constituency at the recent West German Roman Catholic convention - Kohl is himself Roman Catholic - the CDU leader drew only a relatively small youthful audience.
Dr. Kohl's success has been far greater within his own party. Under his leadership the CDU has more than doubled its membership in the past six years, from 300,000 to 700,000. More dramatically, he managed to dissuade the Bavarian Christian Social Union (CSU) a few years ago from splitting off from Kohl's CDU, the senior conservative party organized in the other nine West German states. In federal politics the two parties thus continue to operate as a single unit.
Dr. Kohl's own conciliatory attitude helped ward off the threatened split. So did the nomination of the forceful CSU leader Franz Josef Strauss as the joint conservative candidate in 1980.
After candidate Strauss - who is widely mistrusted in northern Germany - made the most dismal showing for the conservatives in three decades, Dr. Kohl was reinstated as the provisional chancellor nominee. Various other CDU hopefuls kept minimizing him as a caretaker nominee only - pending a real choice in 1983. But when the left-Liberal coalition broke up in 1982, Dr. Kohl was ready. The others were not.
Talk of nominating someone else quickly evaporated - and Dr. Kohl outmaneuvered Mr. Strauss in their first power struggle.
The victory of the genial centrist Kohl over the tempestuous right-leaning Strauss (on the specific issue of when to call the general election) defied conventional wisdom - and could still be reversed. Conventional wisdom held that Kohl was no match for Strauss either in intellect or charisma. The defeat also surprised Strauss, who has regarded himself as the rightful heir to the candidacy ever since the Adenauer days - and regarded Kohl as something of an upstart.
In chronological terms Kohl is indeed an upstart. After studying law and history and getting a doctorate in philosophy at the University of Heidelberg, Kohl became the youngest delegate in the Rhineland-Palatinate state legislature. He also became the youngest majority leader in any state legislature. Since 1976 he has been chairman of the CDU/CSU Bundestag caucus.
Given these accomplishments, the question arises why other politicians - with Social Democrat adversary Schmidt and supposed conservative ally Strauss in the forefront - tend to discount Kohl. One CDU activist suggests two reasons.
* The big-city boys (Schmidt is synonymous with Hamburg, while Strauss can claim Munich) view the small wine-growing, light industry state of Rhineland-Palatinate as provincial.
* As a man who was always a generalist, as minister-president and then as MP, Kohl has never had occasion to develop the specialized knowledge of a Schmidt (economics) or a Strauss (defense). Kohl, therefore, does not shine as they do in detailed debate.
A further factor might be added - a cultural climate that does not gladly embrace conservatives. In the 1930s the right was far readier to make deals with Hitler than the left was - and this legacy has poisoned conservative art and culture ever since.
Thus, when Die Zeit solicited opinions about impending government change from 10 renowned authors, actors, and directors, not one had a good word for the conservatives.
Those who mentioned Kohl belittled him. Novelist Gunter Grass was among the mildest in terming Kohl a ''mediocre politician.'' More typically, director Jurgen Flimm decried Kohl's ''mannerisms,'' ''the empty hulls of his words.''
Nor in the West German news media is there much trace of any American-type propensity to give a new president - despite political differences - the extreme benefit of the doubt.