The MP 0933 and the Comp 911 springs work great w/ the 509 cam. Don't think you need to cut the spring seat at all. Don't know about the stock retainers...I throw all the stock stuff away. I never measured to see how much lift you can run on stock heads w/o cutting the guide bosses down...I always cut mine down low and use positive type valve seals.


CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax