I have a 56 Desoto 330 ci Hemi in my 52 Dodge B3B pickup. I got the Hemi for $250 and then got a quick education on Gen I Hemi's. First off, Pretty much anything before 57-58 does not interchange with anything else; what I mean is that the Desoto Hemi's do not interchange with the Dodge or Chrysler Hemis; same thing between those 2. In 57/58 Chrysler standardized the hemi line. Having said all that, there are some parts commonality between the first Gen hemis and small block Mopars, specifically like the distributor (I am running a SB Electronic ignition on mine). In other words, gen I hemis share more in common with small block Mopars than they do with the big blocks.
You really should check out
HAMB.com, also look at what
Hotheads.com sells. You are going to find that parts for these motors are not all that easy to come by. No one makes a cam for any of the first gen stuff except the 392; you have to have a core which gets welded up and recut. If you really want to enjoy the car and are not hemi fixated, you are much better off putting in a more modern engine. If you want to stay relatively "old school", then drop a newer 383 or 440 in it; if you don't care all that much about being old school, drop in a 5.7 hemi with modern trans and enjoy it; or go to a junk yard, find a 5.9 (360) and trans and transplant that; you get a roller motor, relatively simple EFI, lots of available parts, serpentine system, etc.