How are you measuring the pressure?

Guys, Having rebuilt auto engines including cc'ing heads I'm familiar with compression ratio, etc. I'm using a small compression tester that screws into the head. After run oil is added first.  Then I flip the prop until the reading no longer climbs.  I understand that ringed/non-ringed engines will be different, as will those at various stages of use.  What I am curious about is if I can establish a baseline at room temperature to help predict power and life expectancy. As much for fun as anything else. Thanks for the interest.

I have read Scotts paper and using pressure the way he did with the engine working was very interesting. I guess I was thinking more of using pressure to set deck height. Using it as a base line would certainly be usefull for checking pressure over its usefull life and it would be fun to check different engines and compare them.