Any manual transmission replacing an automatic is a giant leap backward in technology. If you want an overdrive, fit a 700R4 in place of the TH350. It will require fabricating a driveshaft, and possibly tinkering with the shift linkage a little, but it will be mucs simpler, and perform better than a stick shift. Non-GM transmissions won't bolt up without extensive modifications.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!