I don't think there is any useful info from testing with the engine running. IIRC, I found it did not make much difference. I did do it though and wanted to report my findings as well as I remember.

Great news that it is smoothing out.

A leak should affect all cylinders, not just one and it could not affect the compression test, I don't think.

Good luck.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.