I found a set of 906 Vortec heads locally for $200 bucks. They were hot tanked, decked, spring pockets enlarged, guides milled down for more lift, and Comp Cams valve springs, guide plates, and screw in studs installed. The guy didn't know how much lift they were machined for, but for that price I couldn't pass them up. I'm running a Crane 1064 cam (.488"/.510" lift) with 1.6 ratio RR's on the intake side and 1.5 ratio RR's on the exhaust side.

Well I stuck one of them on with an old head gasket and started checking clearance. I don't have a solid lifter laying around to use for checking guide clearance, so I was using a hydraulic lifter. Obviously without any oil pressure it was pumped down and compressed a little.

With the intake valve all the way open, and a 1.6 ratio RR installed, I could see the valve stem between the valve seal and retainer. Not much of it though. Maybe the thickness of a penny. With a 1.5 ratio RR, I couldn't really tell much of a difference. Same with a stock stamped steel arm.

So it's safe to say that once the engine is assembled, I'm going to have issues with the retainers coming in contact with the valve seals, right?

Rather than have the guides milled down more, I was wondering if I can use a dremel and remove some material from the valve guides. With the valve locks installed, there's a good 1/8-1/4" of excess material in the retainer. I think if I am able to remove this, I could gain enough clearance to run this cam.

Here's a picture of what I'm talking about:

 

The "getto grind" is what you are refering to it was used as the cheap fix to the stock clearance problems. I would try and measure the actual clearance... put a checking spring(weak spring) in the place of the valve spring mount a dial indicater one the top of the valve stem and see haw far it travels before contact. I believe the clearace is .060 take your measurement subtract .060 and that would be the safe lift you can support as it sits.Then make your grinding decision.