The big question is can you use 6K worth of parts off the Magnum. The engine is easy, the tranny is not so easy, it's a Nag 1 so not easy to make work, but it can be done. The rear is a fully independent, so a ton of fab work to make it fit, plus I'm sure it is going to be too wide to fit in a 65 Dart. Wheels & Tires, and front bucket seats are probably the only other parts you could use. So, sounds like you should sell the Magnum and buy parts that you can actually use.