i got these heads on a partial trade for my BBC. They are rebuilt, have screw in studs and guide plates so stock SBC rockers can be used. Not 100% on the springs. Stock Vortec can go to .480 IIRC, and seller said about .540-550, so not sure. I was gonna use these on a motor for my 62 burban, but that wont be for awhile. Also have polished valve covers for 88-up centerbolt heads that go with the Vortecs. Selling as a package deal, so not gonna split them up just yet. I have $600 into them, thats what I want out of them. I'll see if I can get some pics. I need 2 more boggers, so these havta go!!!