Hi Jan -
You are getting good advice.
Minor comment... really have to spin the motor rapidly to get a good compression reading (Which really isn’t that hard, with all the plugs removed and the starter motor cranking the engine).
Regarding a leak down test, you have to figure out a good way to lock the engine at top dead center. When you apply the 125 psi to the cylinder, unless you are at exactly TDC, The engine will want to rotate. In our cars you can probably lock it by putting a transmission in gear, and making sure the rear wheels can’t turn.
You will also want to mechanics stethoscope to listen at the intake runners, the crank case, or the exhaust - if you find that your engine leakage is above specification.
you may be taking yourself down a rabbit hole, by trying to fix/test too many things at the same time. Why don’t you wait till your hardware comes back from the shop before you decide that you need to do a leak down test?
They are not as easy to do as it would appear by a quick skim of the Internet, or watching a couple YouTube videos....
But that’s just my $.02
I do applaud you for getting in there and getting your hands dirty.
Rocky