Roller Cam Thrust Button

[Captainfab]

We're still working on assembling my son's 406 and we're having a little issue with the cam thrust button. We're running a Comp hydraulic roller, Cloyes timing set, and a Comp 200 roller thrust button. The problem is with the cam, timing set and thrust button in place, when we go to put the timing cover on, the cover makes contact with the button, but it is almost 1/8" from the front of the block. We tried both a stock timing cover and a Milodon reinforced cover, and both are the same. This is my first time installing a retro roller, but I was under the assumption that it would need shimmed to get ~.008 endplay. Is it common to have to 'grind' on the button? that just doesn't seem to me like a good idea with a roller button. The books we have don't explain much and I've tried searching online for some answers with no luck. Can someone here help us out? TIA