Jerry M has some posts on the CRG website that state what springs he runs. He uses the Comp Cams kit CL-107-3, which is cam an lifters in his world record holding 67 Z/28. No springs come with that kit. I cannot remember the part number of the springs he uses.
Comp recommends 981 or 986 springs. Haven't a clue what the diff is between those two numbers, but guessing the web site has the info.
http://www.compcams.com/Company/CC/c...px?csid=3&sb=2
Unfortunately the CRG forum has been down for a few days. Hopefully, it will be back up soon.