Marcus,
I looked into the AllPro head in the past, when my engine was built. It was rather expensive for the cost. Allpro had special head for supercharged engines, but the cost would have been $5600 for a complete set of heads. I have talked to Mast in the past, but at the time they had no interest in building a supercharged engine in 2008.
Your engine builder is looking for a certain number, and it will vary on the engine size. That is how I ended up with the Livernois cylinder heads. WCCH couldn't do it in the past, because they was hand porting the heads.
Since my car is in Detroit getting more work done on it. I have my engine over at Thomson Automotive. So, last week, here is what I got to drive to feel the power of a supercharged engine. Brian is rather cool because he test out all these parts and gives you the best recommendation on them. Actually, he was one of the designers for the RHS block. Oh, I met Mark Stielow at Thomson Automotive. As you can see it is easy to light up the tires. The bigger supercharger will make more power, but you will have problems hooking up.
Jeff