26915 $155 on ebay
774 retainers $49 on ebay
600-16 Hardened Steel, Single Groove locks 7º 5/16”
601-16 Hardened Steel, Single Groove locks 7º 11/32”
603-16 Hardened Steel, Single Groove locks 7º 3/8”
(the last number is the valve stem diameter, measure yours and order accordingly on ebay from Discount Performance or Atalantic Speed Performance for $8)
These locks will fit these retainers, these retainers will fit these springs, these springs will fit your vortec heads.
I'm not pushing ebay but these two places sell good stuff, good prices, and fast shipping.
Good luck with your vortec heads. I am very happy with my heads on my 327. The only thing I don't like is the intake gasket is expensive when I do a cam change.