Engine Decode?
If your '65 Barracuda is a 273 car, it will be a pretty easy swap. The only real modification you'll have to do is get a crank bushing for the small snout convertor. Everything else should transfer over from your 273. Converting to a 4bbl from a 2bbl. will require modifying the kickdown linkage or getting a 4bbl set. (not that easy to find anymore) or buying a cable kickdown setup from a race supply company. If your car is a 6cyl, you're in for quite a parts hunt. Check some past threads for more on that conversion.