PSI Also Dose a great job helping with valvetrain issues....
http://www.psisprings.com/
If I recall... 340 Dual springs would fit... ONLY if you cut down the guide and also you have to cut down the spring pocket... They were good to like.... .490 lift or there about...
I think "Racer Brown" was were I got the Info.... But I cant find it out in my shop..... Figures.... Sheesh