Everything I've read recently would agree with the above given the 2 choices for a "kit". You may also want to look at the Callies Compstar line. Those are supposed to be really nice "import" pieces. If you were a little closer I'd give you a decent price on my NIB 4.25 Compstar crank. I'm considering a little different route nowadays
Also, go checkout the Performance section over on Chevelles.com. That's probably the best BBC place on the web. Lots of 496 builds over there.