Carburetor size is something I've experimented with for many years and I found it's difficult to go too small. When a 480 runs as strong as a 600 on my 351 I can see no reason to go to 600. After all the engine is only occasionally pushed at full throttle. There's usually vehicles, red lights and speed limits keeping a light throttle as the only choice. So part throttle is where the engine lives. Smaller throttle bores and venturis are always advantageous at part throttle. So even if at full throttle a larger carb is a little better and for my engine it's not, the smaller carb is better for drive-ability, fuel economy, and resistance to bump stall off road. The Comp Cams 35-349 is designed to work from 1500-5500 RPM. My C4 shifts at 4500 and I see no reason to change that. If I had chosen to work for more HP through deep breathing heads etc. a higher shift point would be indicated. I don't need the HP I have. Why would I want or need more? As I stated in my first post the 133 HP of the stock 302 was plenty to do what I need. My "restrictive" 302 heads and exhaust manifolds worked well then and kept working well with a far more powerful 351. I'm going to try GT40 heads that don't change the original look of the engine compartment. I'll see if that does anything. The same with the roller cam and valve train. Headers can never look original that rules headers out by itself even without the noise and heat. The question of going to a 3.85 crank is contingent on things that haven't happened yet and likely won't. The point is to explore ways of gaining low RPM torque that won't break the bank. At less than 2000 RPM all the big cam, big carb, big heads, and exhaust are useless if not harmful. They certainly are not going to improve drive-ability or MPGs.