You don't need lower compression you would want to go around 165 to 170psi for best performance on pump gas. So with that head your going to loose power from stock 150/150 most likely because its going to be in the 140 to 145 range im guessing. But westcoast might be different because dome angles and other things can effect it too.
What I was trying to say was the big pin has a higher exhaust port so if you were to put that head on a big pin it would be 10 to 12psi lower than on a small pin. I didn't know what motor it was going on so thought I would give you both compressions. So In my opinion I would look for a different head or run your stock head unless you want to run less compression.