Funny you mention "Hells Fire" It was owned by a buddy of mine and his Dad from Buffalo NY till a few years ago.
Your right, #2 Speedmaster and a BB Chevy with a Hi Rise manifold, over the transom headers, center steering and lots of other little tricky bits. Quite nasty when it wanted to be that boat.
They have a great wall mural picture of it running Lake Erie on a clam evening right on the step and the drive at about 85mph.
It was never very reliable and in the end they sold it to my brother in-law who sold the drive, gimble and transom plate and is going to be a project boat for him in the future.