Decking a block. How much is too much?

I'm buildin a little 4 banger for my '27 RPU. It's a 153 cu. in. Chevy.
After having talked to the folks over at Clifford, I've decided to deck the block some to bump up the compression ratio. The stock ratio was 8.5 to 1. I'd like to get it up to about 10 to 1.

My question is, how do I determine how much to take off without goin over?

By the way I'm still lookin for an aftermarket intake, and maybe a dual point dist. for this little banger.

Thanks in advance.
Count

 

Need to find CC of the head first and TDC of piston figure out the CC of the left over cylinder from the top of the piston and then go from there don't forget the thickness of the head gasket. Intake, make your own.

 

Bttt for mornin crowd.

 

There's lot more to go into than I'll try to here. A trial fit assembly would be in order to determine how far "down the hole" the pistons are. Chances are the block can't be cut very much or the pistons will start coming out of the bore and then you're flirting with piston/head interference. A bit might be able to be taken off the head also, to increase compression. The suggestion to CC the chambers (or do a search to find out the supposed CC volume), add all the variables, including head gasket compressed thickness, piston valve relief volume, etc. etc., and then calculate the theoretical CR is a starting point. It might take a slightly domed piston to get to 10:1, I'd guess.