I believe they stopped making the 979 springs. Use the 980, just slightly higher pressure than stock, does not use the stock dampner, has an internal one.
Just tried searching Summits site,that pn #cc-979-12 produces no results now. IMO 91# on the 980 spring is taking it to the edge on a stock cam, so now what? does sealed power make a stock spec spring?
I think someone had said that if you remove the inner spring from the 980, it comes out to be about at the 979 specs...Maybe the 980 IS the 979 w/inner spring???
I just bought a set of 979's from a local speed shop about 2 months ago...They should still be available...I would just call Summit and ask...Sometimes their website doesn't seem to give what you're looking for when they do have it...