Budget 360 build

Hey guys, this is my first post on this forum I have a 1970 Plymouth duster with a slant 6 and I plan on eventually doing a 360 swap, I was wondering what's a good budget engine to start with. Should I get a running 70s motor that needs some work? or would it be cheaper to get a 90s 5.9 360 and do a carb swap on it? also what's a good tranny and rear end combo with a 360? Thanks guys!