Depending on where you live in Alabama, you could run an E85 carb and it will clean the carbon out, run cooler, make more power, and never ping again no matter where the timing is set. There are quite a few stations carrying it, and once you get the varnish and crud out of the lines and tank, all you need is a carb swap to run it. Go here, http://e85prices.com/e85map.php
put your town in the search bar and it will show you where the pumps are.
A carb swap is cheaper than pulling the heads, swapping pistons, and works better than retarding the timing and buying race gas. I run it in my 70 GTO, 98 Formula, 98 Gran Prix, and 76 C10. The GTO has 13:1 compression in its 455, and it loves the stuff. The negative stuff you hear is mostly BS, but you will use a bit more fuel with E85 unless you have high compression, over 12:1. The more squeeze you have the less fuel you will use. The difference in my low CR engines is about 2-4mpg.
You can always pull the engine apart, swap dished pistons in and lose power too.
Its up to you because its your car. It just makes more sense to me to use a better fuel and keep the compression, because compression adds efficiency and power. E85 is quite a bit cheaper than race gas, in some places its under $3.