My opinion is that on a naturally aspirated street motor where engine speed is limited, a 4-bolt block is unnecessary.

I'll step out on a limb here and say that the Q-jet is probably the finest carburetor ever built. They're just like anything else in the realm of hot rodding, you have to learn how to set them up and tune them. Doug Roe was a GM engineer who probably knows more about them and how to get the most out of them than anybody else. Read his words of wisdom....
http://www.amazon.com/exec/obidos/tg...books&n=507846