for what you have I think a 3 vane moroso will do the job just fine. When we had our 496ci we ran a 3 vane and it pulled 12 with just the tap of the throttle. No need to buy a big pump if all it means is your vacuum limiter is always letting fresh air into the engine to limit you to 12.
We used a Moroso limiter also. I think it had 4 settings using little washers. From 8 to 16.