An engine can run fine (apparently fine) with lowered compression. The term for 150 PSI is really not acceptable; “useable” or “tolerable” would be better terms.
The general rule of thumb for compression pressure is to multiply the compression ratio of the engine (10.0 in this case) X 20. This would mean 200 PSI and would be applicable at sea level in certain barometric conditions.
Altitude and baro. changes would lower this some so 184 would be about right.
An engine can misfire at 110 PSI but will not likely misfire at 150. There is no physical way of inspecting the rings with the valve cover or camshaft removed. This would involve a complete engine disassembly and this is also why when a compression pressure issue is involved a dry compression test should always be followed up with a wet test.
Wet test means it’s rechecked with a small squirt of oil being placed into each cyl. as it’s tested. If the pressure takes a noticeable jump up then it has a ring problem.
At this point I have no idea who caused what with this engine but my gut feeling is that this car has some issues that were likely inflicted before you bought it; likely abuse or maintenance neglect by the original owner.
(A note about compression pressures. Many shops, mechanics, and even service manuals are frequently wrong or misinformed about what constitutes “good” compression readings. Some think that 150 PSI is perfectly fine but it’s not. The only auto engines that I’m aware of in which low pressures are actually good are maybe a modified hot rod engine or the old air cooled VW Beetle or Bus engines. In the case of VW 130 PSI is fine but you’re also dealing with a completely different kettle of fish there.)