I built an LS/VTEC with Civic Type R pistons and read (yes, another post). I am going to be close to 13:1 compression.(not good for 93) I also read that you can lower the compression with a thicker headgasket. I am wondering if there is anyone that has an accurate measurement of how much each .001" lowers compression. I am not sure if I want to go with the cometic .040" or the .045"
to get around 12.5:1. I am under assumption the .040" gasket gives me 12.68:1 compression with oversized CTR's with a PR3 Head.

 

this isn't going to help you with the headgasket thing, but at least you can get an idea of what your compression is going to be:
http://technet.ff-squad.com/cr-calculator.htm