Look at the pics.
They have offset pushrod holes, they are not OEM.
Dealer/factory performance part, yes.
I think the casting number is different than a regular 974 head, either way they've offset pushrod holes like a TA.
Thats why i say the numbers are disappointing. I and others can get 240's on average by .400 and 260s-270 @.500
They are very average heads. Historically significant, a collectors item. But for being an offset push rod head... they are barely worked.
Id use another head.