What valve springs should I use?

Might want to do a double take on that cam lift.
I think that's pretty close to valve guide seal/retainer contact on the Magnums.
Hughes sells a spring, retainer and lock set just to solve that, but I think Magnummopar on here can make you a better deal on them.
Pretty sure I remember him saying that, but I could be wrong

The stock springs are sissy's. :D

Dang, I wish I would have known about magnummopar before I ordered from Hughes today.

As for my cam, it is a Summit 50052 with .454" when used with 1.5 rockers. So it should be around .484" with the magnum heads.