Id have to disagree with mag 68. Ive had a 502/502 in my 68 for a year now, and not once have I had cooling probs. And thats with my stock 427 radiator and water pump. Crawling in traffic and on the highway, no prob. about 2 months ago, I did put on a edelbrock water pump, not due to cooling issues, but as a weight saver, as my stock water pump was 33 years old, and sooner or later, it was going to go.
I replaced my 427 with the GM 502, and the neat thing was is that my OEM intake (L-68 tri power with carbs), distributor, water pump. starter off my 427 fit right on my 502. Drawbacks is that headers for the 502 DO NOT bolt right on. Due to either the angle of the heads or the headbolts, headers will not fit directly on, as the header flanges bump against the head bolts. Modification to the header flanges mut be made, at least with my headman headers. Some other folks with 502's have mentioned they have had the same issue with headers. Oil pan that comes with the 502 WILL NOT work without mods to either the oil pan or cross member. Its a close fit, but will not clear the cross member. One member tried grinding a little clearence on the oil pan, and went thru it. You might be able to grind the cross member, Im not sure. I ordered a GM performance pan that will clear the cross memeber. Its about $130, comes with PU, dipstick, one peice gasket

Id drive this motor anywhere, anytime, with no worries. But then again, the price these things cost, you should be able to

I run my original M22 4 speed, and everything bolted right up. There is no boss for the clutch linkage ball on the block. You must make a bracket, or order one http://www.sdpc2000.com/cart.asp?act...=1006&pid=8875

As far as streetability, it purrs like a kitten. Just enough cam for a rumble on idle, and has pleanty of torque.