What size valve relief tool?and stem diameter?
 

I will be cutting reliefs for a 2.05 valve and it says to get one size bigger than your valve to cut reliefs. Isky offers a 2 1/16(2.0625), or a 2 1/8(2.125). Which should I get? Also, I need to know the valve stem size. They offer 5/16, 11/32, and 3/8. Thanks, Jason

Use the 2 1/16" and the 5/16" cutter. This will get the job done for you. The LS1 uses a 8mm (.3149") stem, so the 5/16" (.3125") is the closest you will get. The 11/32", 3/8" will not even fit in the guide. :)