Like you've been told, this isn't a 426. It's first generation from the '50s.
Depending on what it is, a Dodge, Chrysler, or Desoto Hemi, though, places like Hot Heads and PAW have parts for 'em. Each manufacturer had it's own series of engines before the 350 was introduced as a "corporate engine."
http://www.hothemiheads.com/
http://www.pawinc.com/
As a matter of fact PAW was
the place to buy parts back in the '80s, for all makes and models before Summit and Jegs came along. Now, they do just the 1G Hemi engines.
The downside to 'em, their heavy. With horsepower capabilities about the same as an LA, which comes in lighter. And parts ain't cheap. But cool! Definitely makes one helluva conversation piece. We have a 392 sitting on a stand here that always get attention.
The biggest thing about the early Hemis was the wide range of uses. Industrial engines, marine engines, truck engines, as well as passenger car. With the trans hooked to it, it's clear from the pics the Hemi you're looking at is a pass car engine. But if you find one sitting on the floor, or just laying around, do a lot of research on it before you buy it. Industrial engines and truck engines sometimes got less desirable heads (for flow) or odd cooling systems that make it a bear to put into a car.