If the body is good $2,500 probably isn't bad. It really comes down to questions of rust and paperwork in my mind. If you didn't get a clear title you paid $2,500 too much. If you got a clear title and minimal rust to repair you did pretty well.
A '49 1-ton would not have a 235 from the factory. Does it have two valve cover bolts or four cap screws around the edge of the value cover? If four its a 235, if two its probably a 216.
There is no kit to put disks on the front of a 3800. The guys who have done it have worked it out on their own. A little searching here should turn up some tips on how they did it.
