If you really want to know what compression ratio you have, and have a target, or you are concerned something may not have adequate clearance....I recommend....screwing around with a dry build to determine the thickness of a base spacer or thicker head gasket, or combination....
.....and even a bit of plasticine (modelling clay) work, etc. It's all good engine build practice, working on knowledge, not ignorance.
It is what you should do because we don't know what you didn't tell us, i.e. what was fitted previously, your barrel deck height, chosen piston, cam lift, valve size etc.
But, if this is all pretty standard stuff and all you are concerned about really is too much compression for local fuel....I doubt you need to do more than confirm nothing hits....
From the photo we can (just about) see your head hasn't been skimmed 0.040", it's most likely less than 0.020", probably less than 0.010", and was done to return a flat gasket surface, possibly after a blown gasket.
Remember, if it's an 850 it may never have had a base gasket, and it is better not to use one, Threebond 1184 is good. If it had one, or two gaskets and/or a spacer, someone has been here before you!
