If you do go to he 230-250 enging hang on to the 194 head it will increase the compresion on the other engines. I have one in my 65 and am in the process of gathering parts to put TBI on it, the biggest problem with the 194 is it doesn't have the boss in the back of the block for the clutch linkage, had to fab that but it turned out OK. Mine has a T-5 in it but that would require a open drive line.
