**** 360 Piston Options ****

Re-check your WH405CP CR; the top is a dish, not a dome, so the dish volume should be added, not subtracted. The CR should be only fractionally different from the 405CP, if at all. The W stands for 'individual' (not a set)and the H stand for hypereutectic, and the C stand for coated skirt, but they are the same pistons. Both should work out to around 7.6:1 SCR, not 7.0:1, with 69 cc combustion chambers and .051" head gaskets (the number I used for standard Felpro's).

http://www.fme-cat.com/digipubZ/sealed-power-vintage/#?page=402

I hope you will forgive me for saying so, but one problem with the above calcs is that you are modifying from your original CR number of 7.5 based in the assumption that the old pistons were flat topped. Is that known to be the case? (I am assuming they are not...) Plus you are starting from a number derived from a static compression measurement. That compression measurement is limited in accuracy and in its translation to SCR. It is more accurate to work with straight computations.