71 Dart get 408/ Trick Flow Heads....

have had a 260/264 Howards flat tappet in use for 4 seasons with edm lifters, its now in my new 418. Zero issues, lash stays constant
That's the hardest thing about this hobby is the inconsistency. There are also quite a few guys on the forum successfully running hughes grinds but no matter the company or part all it takes is one bad day in manufacturing and some customer is going to get screwed.