There was a more recent discussion that had comments by an internet purveyor of these heads, rods, etc. Take a LOOK
at this thread. There are dozens of mentions of these heads here on this forum and elsewhere.
I never received any sort of definitive answer to my (rather important) questions as to the heat treat specs of the aluminum as well as the material the valve guides and valve seats were made of.
And until I do, I wouldn't even consider
using them; that the seller himself had no clue other than "According to our head builder the seat material is just as it should be."- which is a non-answer, AFAIC- does not bode well for them.