I ended up just grinding the heads of the problem bolts down until it clears OK.

I hope you don't ever have a problem with your hard drive cables (not an uncommon occurrence) because you will have to be able to remove those screws in order to get access to the drive cable where it connects to the motherboard. Those screws are tight, and if you have thinned down the heads you may not be able to get a screwdriver to grip them hard enough to remove them.

tanstaafl.