Leak Down Test

I'm testing the leak down on one of our Vistas. It hasn't been hitting right on #1 and possibly #2, it's hard to tell so I finally decided to open the leak down tester that I bought a couple years ago. Setting my compressor at 100# and testing through the center hole in the energy cells with the cap and guts out I put a large rubber ended hand held valve pressed into the hole and it works very well I think. If your not quite TDC it will start to roll the engine over so I back it up or forward it until it stays put. I'm getting readings in percentages from around 28% on the lowest to about 40 % or maybe 42% on #1. Sounds like it's going into the crankcase, not the exhaust or intake air cleaner hole. If I don't have it turned quite right and a valve isn't quite closed you will hear the hiss there.
My question is what % might be an acceptable level on a ice cold engine. It had been bored 30 over years ago and I put new rings in it after it sat for several years. Pistons looked great, have had injectors in and rebuilt and pump too since that time and never thought it sounded quite right, muffled beat but now it has gotten worse so I'm trying to locate the problem. Number one is the last cell cap to always warm up so that's been on my radar when I was still trying to run it, then parked it until now. I can pull the front head but probably won't see anything from the top unless the cylinders are scored or something obvious. Could the head gasket be doing something under high compression?
Thanks for any help.

Did a GM 5 cylinder. Leak could be heard in crankcase. Ended up being valve seat.

I did a lot more testing this afternoon and when I get them at the very top all test out in the 28% to 32% leak down and actually that number 1 is probably the best of any. I'm putting the cell plugs back and going to take it outside and run it cracking the lines and first check the timing again. I can't recall if I switched injectors around 2 years ago trying to isolate it or not. If it's not a fuel issue I guess I'll pull the front head. That doesn't seem like much leak down does it? It's still a very tight motor even with the plugs out it doesn't turn that easy with the fan.