Its really cool that you got that Dart. Should be a good runner, while you do your upgrades. A body parts are plentiful and usually cheap if you're patient. Post what parts you need, when you need them I'm sure we'll help you out. Keep your eyes out for a 73+ 4dr (w disc brakes) to part out and you might be able to get your big bolt conversion pretty cheap once you sell of the leftover parts. Congrats again!

PS, whatever upgrades you do for now be sure to keep the Dart running and driving, and make sure you have the $ for them before you tear into it.