Here are two versions of the tune.

ORIGINAL VERSION, from the sheet music. It's in D minor, although the singers on YouTube sing it in Bb minor, the key in which it was sung in the show Allegro.

https://m.youtube.com/watch?v=QpMbxeeRJME

https://m.youtube.com/watch?v=jUFO2tUBV4c

https://www.scribd.com/doc/271984697...a-Dope-Allegro

Gentleman Is a Dope (Orig), The - Richard Rodgers

MY VERSION, which is slower and has a number of different changes.

Gentleman Is a Dope-Rev JE, The - Richard Rodgers

Cheers,
Jer