To much cam??

You put in cast "9.5:1" pistons. Did you have the block decked? Me thinks your "9.5:1 383" is closer to 8:1. The 383 block is ALWAYS very tall compared to the blueprint spec so you have to mill the hell out of them to get the piston to where it needs to be. Plus, the 906 heads will have much larger chambers than blue print spec especially with a valve job. Were they CC'd to verify the size and mill the heads to correct that? 383s are harder to "get right". Yours is overcammed only because as you describe it - it's about 2pts less static compression that you wanted.