A 400 Chevy is not the same engine as a Pontiac. It's still a good engine with lots of torque, but br VERY careful not to overheat it. The heads have a nasty habit of cracking with even a little overheating. A 400 is the same size as a 350 externally, but it has a bigger bore and a longer stroke. It uses an externally-balanced crankshaft, which requires a different flywheel and harmonic balancer than any other smallblock Chevy engine.
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!