Nice ride. What year is the transmission? As it is the one that came with the car back in 1962, then the converter it came with with will be a 12" (aka as a 11 3/4") narrow ring gear, 19 splines, an no weights. It was rated as a medium stall, and from the information I have, it stalled between 1900-2200 rpm. It is the only (other than the Hemi Converter) that is listed for the 727 of your vintage (1962-1966) no matter what engine is in front of it, that I have in my converter catalog. It ran fine for many years with the factory supplied drive train, and really, for what you are planning to use the wagon for, I really can't see much sense in changing anything. Get your original converter rebuilt. I'm sure there must be a converter rebuilder in your area.
Others have mentioned contacting various auto parts outlets. I'm not knocking these stores, but the people that work there usually have a very limited amount of knowledge about automatic transmissions and torque converters. JMHO and don't let price be your guide.
Have fun, and that's going to be one nice ride when you've got it finished.