Not to be too much of a stick-in the mud but if it's 150 flywheel HP that is expected it seems like a lot of work. A well done GX head with 14:1 compression gets pretty close to that with minimal work. If it's 150 WHP it may be slightly out of reach of the GX head done really well.

In any event, if you are going after 150 to 200 flywheel HP you are probably going to need uprated rods, forged pistons, big cams, rocker modifications and a great deal of crankshaft work. This would all still be cheaper than the prospect of adapting a different cylinder head to the block and you would still need to dao all of it. I would say find a GX head and do all the proper work that you can think of and have a reliable package.