With regards to the head, look for a relatively common 56-63 235 head, with a casting code of 3836848.
If you are going to spend money on reworking a head, do it on an "848" head. I plan to just get a machine shop "head job" done on a "848" head for my 1954 235 that I will eventually rebuild.
My guess on hp is that with an "848" head, dual exhausts, 261 cam, and any bigger carburetion, you could get 150 hp or maybe a litle more.
My appoach to carburetion on my 235 is now "keep it simple". I'll be looking for a 1-barrel 248 GMC Zenith carb with a variable jet. It may not look cool, but it will be simple and reliable and give a fuel-feed equal to the needs of the engine. I'll find out if that is too much carb.
