john, I would have to think long and hard about changing the chamber volume. You have the perfect static compression ratio for pump gas at 9.1:1. If you use the World heads with that tiny little chamber (actually designed for the 305 Chevy motor), you'll raise the c.r. to 9.7:1. Now, depending on the squish that Chevy built into the motor when they machined everything, it probably wouldn't run on pump gas any more without detonating and disassembling itself. The other thing is that by raising the c.r., you are changing the cam requirements to a longer duration design, exactly opposite what you want for good street manners. That long cam you have spec'd out will be the biggest pain in the ass you can imagine. No low-end torque without a 3,000 stall converter and very little intake manifold vacuum to operate accessories like power brakes. Furthermore, I would never run a single plane intake on the street. They are meant to be used on a high-rpm motor and won't make enough power down low to move the vehicle without (again) a high stall converter.

Take a look at these dyno-proven combinations and see what they did for parts combinations to achieve the numbers. For a street motor, look for the maximum torque at the lowest rpm's (for instance, over 400 ft. lbs. at under 4,000 rpm's). http://www.ryanscarpage.50megs.com/combos1.html