Look at what TF warranties when you buy the assembled heads.

I've had 4 sets of the TF 240's here, and frankly I thought the parts seemed perfectly fine.

The only caveat for me is, for many solid flat tappet cams, I'm not in love with either of their spring choices.
One is a little lighter than I'd prefer, the other too stiff.

No way would I bother with bare castings.
That's just a way to add hundreds of dollars to the heads.