hmmm, I can't recall seeing a red block with 200psi... I have always went by a rough range of 130-160 as being considered normal for these engines. My current runners(3 240s) all test in the 145-160 range and have for years, with no noticeable difference in performance on my lowest vs highest compression car, none use an excessive amount of oil. But obviously, there is some difference in opinions. I don't work on anyone's car but my own, so my opinions work for me but might not be textbook correct or suitable for others.

But... needless to say, once he fixes his massive vacuum leak, his car should idle properly and will run as good (or bad) as it did before the leak popped up.

 

I'm not saying your wrong, if my source is right as to 9.8 compression ratio it should be higher. which maybe not be accurate.

I'm basing my number off other cars which most 4 cylinders are 165+ really more like 180.
My 740 just tested shy of 160 Im guessing,the compression ratio is lower being a turbo.

 

150 psi is normally good compression on these engines, so his compression while not perfect is just fine, and NO, he hasn't lost 70+ lbs of compression--a NA Red Block has 114 HP when new...

 

I had a similar symptom that was solved by replacing the intake manifold gasket. I would try that before spending more money on other remedies.