How much should I expect to spend.

To put in a 360 using all the 273 parts possible you will need the 340/360 conversion mount from Schumacher (left side is unique to 273/318 or 340/360), plus either a new convertor with the larger (later) crank hub, or the adaptor to let the early convertor work with the later crank hub. To go from a 273 (internal balance) to a 360(external balance) you'll need the flexplate from B&M. With no other changes, and assuming the radiator and support systems are good, you will need to spend at least $400-$600 on it. The V8 '65s ran 7 1/4 rears, but you are increasing the torque by about 40% I think so an 8 3/4 should really be a part of the deal sooner rather than later. For that, add another $600/1000 depending on location, gearing, and quality. Lastly, with paint, wearbles, and basic stuff, add a couple hundred onto it to get it in and running, and another few hundred to have the exh upgraded.