AED did a 5.0 stroker, 10:5 compression, stock bore teksid. Custom cams, ported heads, it made 980rwhp SAE.. and well into the 1k range on pump E85.. On C85 it made 1000rwhp SAE.. So it has been done.. Again with .3 more displacement and less heads and probably not as good of cams you aren't going to get close.. Also that was a 2.9 crusher on a 3.0" pulley and stock lower.. So it's got more in it..
My suggestion: cancel the order on the 8.5 pistons and go 10:5..
Its too late to change compression unless i want to pull the motor apart again