Solutions for too much compression

Damn....
First off, you are supposed to remove and PLUG the vacuum advance line when checking timing. You are looking to check the mechanical advance rate and amount. Most stock LA and B/RBs will make the most power with 8-10 degrees initial and 33-36 degrees total. A higher performance engine with more cam and compression often need MORE initial, something starting at 15-17 degrees.
My own 440 based 493 runs 18 degrees initial and 34 total.
Secondly, the belief that using a bigger cam to "bleed off cylinder pressure" does not always work out. That theory is based on the idea that the bigger the cam, the more overlap that it has and that supposedly reduces cylinder pressure. The fact is, it does.....BUT only at low engine speeds. That big cam starts to close that gap as rpms increase and at high rpms, it builds a LOT more cylinder pressure and will knock worse, maybe rattling the engine to death while you can't hear it over the moaning exhaust! I have dealt with this personally. I was close to 11 to 1 in my engine and was looking for some way to stop detonation. I was stupidly stubborn and did NOT want to pull the engine to put in dished pistons. I sent with Cometic .075 head gaskets to lower the compression. It is a crutch, but it did work. A better way to go would have been to use dished pistons and regular head gaskets. I would make more power and have quench that way.