My friend has a LS1 and is thinking about installing my old 5.3 heads. The heads are not cut but are ported with bigger valves.
I think the compression will be 10.8? Would this be alright for a 100-200shot with the right bottom end. I don't know how this compression will work with pump gas and the jug. Anyone have experience or suggestions? Thanks for any help.

 

Its gona be fine, but after the 150 I would thrown in octane booster or a splash of race gas to be on the safe side.

 

I'm running 12.5:1 compression with a 200 shot. As long as you address the fuel system properly, you'll be fine.