If that 62 engine is a 235, it's close to a bolt-in swap. The front motor mount bracket will have to be adapted, as the GMC engine is about 2" longer than the Chevy. The bell housing, transmission, rear crossmember, and clutch linkage should be a direct swap with the corresponding Chevy parts. The 230, 250, and 292 engines will require major 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!