Yes, the compression is low. Try doing the compression again but this time put a couple of good squirts of oil in each cylinder. If the compression improves, the rings are likely the culprit which explains the blow by. If it does not, valves, valve seals, valve guides are the likely culprit. I agree, the plugs are a little cold. If you can’t find the AC plugs, Champion j12yc or j14yc or the resistor variant will work. I run j12yc in my 235 and 261 builds. More out of habit then anything else.
