I just recently got a killer deal on a set of m50 CP forged pistons 8.5:1. The issue is I am rebuilding my m20 b25 for a turbo build. I have a s52b32 crankshaft, s52 rods and other goodies. I called Vacmotorsports to see if the m50 pistons would fit in the m20 block and they said no. I was under the impression that all I needed was a head spacer, can anybody shed more light on this. I would really hate to buy another set of pistons over again, thanx