FWIW, I, too, had a very expensive rebuild as the result of a flat-tappet cam wiping some years ago and have taken extra measures since then w/ FT cams to try to mitigate that happening again. If spending another $150 at that time to nitride the cam would have reduced the likelihood of that happening in the first place, I would have.

Also, since you can't get an EDM-drilled hydraulic FT lifter, consider grooving the lifter bores or going w/ the special Crower hydraulics that have a small machined flat on the sides of the bodies to allow for more oil getting to the lifter/lobe interface.

One last item... do the HL Comp cams have the same reputation / issue w/ valve train noise & instability as their standard Xtreme hydraulics? If so, I'd suggest looking into what other lobes might be a better choice, unless you're RPM limited already.