I had a similar deal as you with a 216 in a 52. It smoked a bit. It had a crack in the water jacket that sort of sealed up with radiator stop leak, . I ran the crap out of it for years as is, because I knew that I would never rebuild it given the crack in the water jacket. It started and ran great all the way up until I tore it down to scavenge a couple of connecting rods for another 216. I would say do what HRL says, and run it til it don't.
Carl


1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission