Maximum advance curve on my 360

That sounds a little odd that you can't put anymore than 27 degrees in your motor with only 10.1:1 and that octane of fuel. I wonder if your balancer is off and you really have more advance than it seems? sure sounds like it. Most LA's with stock heads and decent 9 or 10:1 compression like 32-34 degrees total and can handle that much with decent fuel. I'd check your balancer.

Chuck