Need your help on 383 Dart exhaust

Ok, this is what I got . . . 73 Swinger with a lil 383 dropped in and running. Just bought the car, don't have it yet (mid June). Problem is it doesn't have any exhaust on it. Presently it has exhaust manifolds (supposedly for the application, 383 and A-body). He is including "down pipes" from manifolds to bottom of engine bay. Summit / JEGS offer header back kits, but I have manifolds. I'm trying to keep the cost down, and I really don't want to tackle the pain of installation of headers at this time. Should I just bite the proverbial bullet and install headers? Eventually I do plan to. I'm looking for full exhaust and will be adding stock style 340 tips. Can I get manifold back exhaust kits? I'm looking at 2.5" pipe. Friend sez I should go 3", but with manifolds? Any direction would help! (too many choices . . . not enuff brain cells . . . lol) Thanks, Rog