Sorry guys, I should have included more info. I am running the '509 MP cam and have Edelbrock aluminum heads. It couldnt tolerate much more than 31 degrees of advance even when using Californias dog water 91 octane "Super" unleaded 15% ethanol gas. I used to run the distributor w/o the vacuum advance, but after reading articles in Mopar Action and from other sources, I ran a line to it and will keep it that way. The pistons are actually at .017 in the hole, and with the .039 gasket, I'm probably already at the edge of losing quench anyway, right? .039 + .017 = .056.
I ran the Cometic MLS gaskets a few years back and the car ran great. I believe they were custom made and .060 thick. I was able to increase the spark lead to 34 degrees and the motor felt crisp and responsive. I ended up pulling the heads when I found stem wear on some of the valves, and I couldnt afford to buy the Cometics at the time of reassembly. I had a set of Fel Pro 1009 gaskets so I used them instead.
A thread on the Race forum asked of the percentage of power gained/lost with compression changes. The consensus in the past was that each point is worth 4 % of power, EXAMPLE: An engine that makes 400 HP with 10 to one should make 416 with 11 to one. This of course assumes ideal cam conditions and zero detonation. The thread had many opinions and even some actual real world research showing the tested results to be lower than that, often in the 2 % range. I would gladly give up 2% of 500 horsepower to gain more streetability and to avoid having to pull the motor apart every few years!
The 440 Source website listed a no name .051 gasket for $15. I was a little suspect of its quality, partly due to the Wal Mart price and the lack of a brand name. Thanks for the help.