Bore, stroke, rod length,Scr, Ica, and elevation
then go here,
Wallace Racing: Dynamic Compression Ratio Calculator
and pay close attention to the V/P, which you can read about that here
V/P Index Calculation
to get a picture of where you are starting from , plug 7.8 in for Scr and 50* for the Ica,These are the specs for a stocker with a 240/248/112 cam, in at 110....
plus the basics; 3.91x3.315, 6.123rods, and your local elevation; 300ft IIRC. I get 132psi@109VP, and you already know what that feels like.