Best engine for a 63

Hey all, we just picked up a 63 Econoline for 800 the body's mint, interior sucks but theres no engine...i want a straight 6 that will run with the rear end thats already on there. Anyone have any ideas what engines will suit it best?

I m sure that you have done the engine thing by now but a guy in our Van Club could help you out in the future.He has a 305 in his 65 bout is putting a 6 in his 64.

Car Motors :170ci,200ci, **possibly 250ci ** Taller motor than others has 2 barrell carb all 6cyl ,,,sources are Mustang Falcon Comets Fairmonts Zephers ,, Automatic Trans would perform same (if auto now)or better than Stick