What is my compression with L2316 pistons

I am doing a build on a 340 and am considering the Speed pro (used to be TRW) L2316 pistons. I have read that they are the stock replacements for the 10.5:1 compression 340. I know I will have to take measurements but just off the top of my head with stock J heads I should be right around 9.5:1. Does this seem to be a fairly close guesstimate? Are they an exact duplicate of the original 340 pistons as in how far they go above deck?