Hydraulic Roller Lifters w/LA Block?

Does anyone here have experience with running hydraulic roller cams in a small block Mopar motor?

My 340 LA block is currently being rebuilt at my local hot rod shop. I dropped by the other day to check on things and they showed me a very strange problem they are trying to solve with my new hyd roller lifters and comp hydraulic roller cam (20-812-9).

It appears that the tops of the lifter bore castings on my block are fairly inconsistent. Some have a bit of a chamfer or bevel around the bore hole while others do not. The depth & size of the ones that do vary. The problem is that with some of the lifters, when they are at their highest lift position, the oil groove/ring in the middle of the lifter actually pokes above the top of the lifter bore a little bit. This is obviously not good. See the attached images for reference. Quick video here: [ame]https://youtu.be/ggilUawdYlk[/ame].

The shop said they've tried 4 different sets of lifters with this cam so far (Comp, Shaver, Isky and now Morel) and they all exhibit the same issue. The head engine builder there told me he's never seen this before and right now his best idea is to have the cam's base circle ground down a bit to allow the lifters to sit further down in the bore but that sounds pretty drastic and will cost as much a whole new cam.

Is this a common problem or do I just have a particularly crappy block? Does grinding the cam down sound like the best course of action for this particular issue?