CR calculation, deck height/effective dome volume?

Just working out the volume above deck for the .036" above deck, I get 7.7 cc's above deck with no eyebrows, and since the eyebrow volume is likely in the 5 to 6 cc range, then your 2.2 cc number looks about right. If you want to use this number in a formula, then treat it like a domed piston with deck height = .000" and a dome volume of 2.2 cc's.

However, there are easy tool to compute the SCR without all of this rigamarole. You can just directly enter numbers like the +.036" deck height and the eyebrow volume, etc.
See here for the one I like: Dynamic CR

BTW, .036" deck height is not normal for a 340 piston. If it is a stock-like replacement (which I would expect your Speed Pro pistons to be), then the deck height would be around +.018". Are you sure you measured this right? Or has the block been decked?