440 Hemi heads Question

Hi all a few years back I saw an add that had Hemi style heads for a 318, 340, 360 and I think the 440.

The heads produced 1.5 HP per cubic inch. Im not sure who made them or they still make them.

I wanted to know if they are still on the market?

Who makes them?

Has anyone ever used them and are they worth the money. I want to build a 700-800+ hp motor for my Coronet R/T.

Thanks everyone.