Exactly........ well kinda.
https://www.google.com/amp/s/www.motortrend.com/how-to/mopp-1303-cylinder-heads-light-headed/amp/
If Mancini had a bunch of those to unload, they should think about having some rockers, based on their in house HS rockers, sourced for those heads and offer them as a package deal.
The headache for most, as JM pointed out is........ no off the shelf rockers available.