[jims69camaro]

your bore size and the size of the combustion chamber are what affect your combustion ratio. the smaller things like whether the pistons are dished, flat top or domed, the height of the head gasket and so on add smaller changes to CR, and when it's all taken into account is when you get the true CR number. your cam won't affect your CR.

i'd see if i could pull the numbers off the block and check with Motec.com to see if you can get a better idea of what block you've got there. you could have an '88 block with vortec heads and it doesn't necessarily have to be an L31.