The standard V8 bellhousing for the 61 will bolt up to the 454- - - - all Chevy V8's have the same bellhousing bolt pattern, small or big block. Steering and exhaust clearance might be an issue. Be sure to use enough radiator- - - -even a stock big block needs a lot of cooling, and a hot-rodded one really develops a lot of heat. The aftermarket motor mount crossmember might have some clearance issues with the torsion bars, so do some research there before selecting a supplier.
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!