Ok, here's what I did, (I don't exactly recommend this but it seems to have worked for now)
I reused the 350 heads that were shaved to the max along with stock 350 head gaskets. Carefully drilled the steam holes in the gaskets and put it all together. In worrying that the drilled gaskets may not seal right, I smeared a small amount of FIPG around the drilled holes. I put it all together and I am no longer getting coolant in the cylinders. Compression on the cold, non-broken-in engine was right around 150psi. It runs fairly well with the exception that if I rev it hard it will stall as it returns to idle unless I pump the throttle. Thats obviously a carb issue so the next thing will be to rebuild the quad.

Thank you every one for all your advice