Roller Cammed 318/360
The only thing stopping you from doing a roller hydraulic cammed motor relatively cheaply is finding a 360 or 318 that was built stock that way to begin with. I did it with an LA headed 360 about 7-8 years ago. At that time there was little in the way of hydraulic performance roller cams for small block mopars, so I was kind of in uncharted waters.
After studying cam profiles and talking with comp cams about the project, I made some choices. Their thought was that the stock mopar roller tappets would be fine but the big key was getting the correct valve spring open and closed pressures.
The cam I used was a custom grind from comp cams - the springs were a little tricky. After alot of digging - I found some Isky springs that fit the bill for my grind that did not require spring pocket machining. Used the stock mopar roller hyd lifters and went with adjustable valve train. Custom length pushrods were neccessary. Again - This was a LA headed engine.
You may end up spending around 200-400 bucks more doing it this way, assuming that you would end up using adjustable valve train anyway with other types of perf cams. You could also have the original roller cam reground to a new profile as well to maybe save some $. Hughes engines used to offer this service.
Personally i found the exercise of piecing this thing together an interesting project and the result was quite good. Car runs well and has tons of torque - which is what I wanted.