first of all here is what my setup will be, ls block hot tanked honed and decked, stock rods, new oem bearings, new gsr pumps, b16 head with gsr cams, obd1
Will there be a major difference if i do pr3 pistons versus the original ls pistons?

 

yes a big difference in come pression with pr4 i believe it will be like 11.3:1

 

yes a big difference in come pression with pr4 i believe it will be like 11.3:1 ls pistons the compression is only like 10.5 but if you search thers a lot of posts about it

 

Don't use stock LS pistons. They don't offer that great of CR. Try using B16 pistons, even some CTR pistons. Crazyest pistons I've ever seen.