How much cfm's for a BPU 351w?

Boring the cylinders has really no advantage power wise, as at most you would be adding 6-7 cubic inches. The only reason to bore the engine is because the cylinders are showing wear, and you want to "true the bore" up for new pistons.

as for your other questions;

1. Any make or model he is comfortable with will work fine. I prefer the Demon carbs, and Edelbrock intakes, but I have also run a lot of Holley, and a Carter or two. I would stick with the 650-750 CFM size with any carb he gets. The Demons run a bit large, so stick to the smaller edge of the scale with them...and the Carter/Edelbrock carbs run smaller, so go a bit on the big side with those.

2. Hedman and Hooker both make nice headers. I would run a 2.5" exhaust. It leaves you room to grow, and will work nicely.

3. Roller rockers reduce friction, and they will help in that regard. He might pick up 5 or 6 horsepower, and they will stabalize his valve train a bit. I have always run them.

4. As for his HP and torque, that is difficult to predict. Depends on his compression ratio, what cam he has, and which cylinder heads he is running. He could get 250-300 horsepower fairly easily, and plenty of torque.

I hope I was of some help.

87