Your '65 is an A body version of the Barracuda. There are several supliers of torsion bars. Probably the most economical is if you can catch te ePST version on sale for $200. Otherwise, most are around the $300-350 range for a set and the most knowledgeable suplier is probably going to be Firm Feel. Talk to them about your car, package, budget, and driving style and they can recommend a good size for you.
btw, Welcome!