Get some lt-1s and be done with it. If you get comp 980's you'll have to shim them to get the correct psi.
Edit: The napa part number for LT-1 springs is : SEP VS739R Thats for 1 spring, you need 12. It doesnt hurt to double check them with a valve spring tester to be sure you're getting 105+lbs of seat pressure at installed height.