What to do?

[RanciD]

Ok I need some advice on what I should do about buying a car. On Sunday I'm going to look at a blue '89 S13. It's got a couple of problems..

-Knocking engine
-Automatic tranmission (big problem)
-No passenger seat (other seat is just a gray base model)
-No keys
-Driver's side fender and front bumper need to be replaced. He will give me both of these with the car, but not painted.
-Large scratch across the door (he described it as almost to the point of a dent I think)
-Dent on roof from a golf ball that he was in the process of repairing
-Trunk leaks, most likely just needs new lining

The positives are it's a coupe, it's blue (my favorite color ), he says it has no rust he could see and it's close. Other than the problems above, he said the car looked great. Now I've been thinking and it seems to me that this might all make sense. If the car was hit near the front (explaining the need for a bumper and fender) then maybe the radiator was damaged at the same time. Could this be the cause of the knocking? If this is what happened then who knows what else got damaged in there, and what condition the engine bay is in.

Do you guys think it would be cheaper to try and fix this thing or just keep looking and buy one that actually runs? If the radiator is the problem and I replaced it would the engine have already been hurt from the knocking or would it be alright? I just really need some advice about what to do. I'll bring pictures of the car after I go look at it.