Technical 454 with 402 heads?

Hey guys wondering if I could get some insight from anyone here.
I'm building up a 454 out of a 80s 1 ton and looking at putting some 402 heads on it, supposed to be 107cc. I wanna run the stock pistons but wondering what kind of compression and power I could expect. Did a calculation and came up with about 8.25-8.5. Does this sound right. Not looking for any crazy hp but 375hp be nice. I'll swap in a mild cam and aluminum intake as well.
Any help on this would be great.
Thanks in advance

 

Stock piston? Flat top 1 valve relief? You really measure how far down in the hole the piston comes up on TDC then what gasket are you using that should give you a better # than a guess.