Edelbrock AVS2 Carb Dilemma

Those who say go the 500........what if he wants headers later on? What if he wants to upgrade the camshaft? What if he wants to swap in a mild 340 or 360 later on? Then, he has to get a whole nuther carburetor, instead of being able to step the tune up on the one he already has. That 650 would feed a mild 408 with the right jets and rods, yet in stock form is perfect for his 318, IMO. At the very worst, he'll need to swap in larger metering rods to lean it out a little on the primary side. That's my opinion and I'm stickin to it.