733i questions

I'm looking into buying a new car. Well, not a new car, a 1983 733i. I haven't had the pleasure to fully look the car over, but I'm curious if there are any recurring/well known problems to look for in the car. It's a 5speed manual, 200k miles. Body looks nice, but again, I haven't had the chance to go and really examine the car. I've been told the car runs strong, but anyone know about how long I could expect these motors to run before a swap/rebuild? Also, how are these things known for upgradeability? Perhaps dropping a larger motor? I want a nice car, nothing street racer, just a nice car that can move when it wants to =) The person is also asking 1500, but I feel this is extremely steep for the high mileage. Any tips/hints/known problems/anything you know about the car would be greatly appreciated. Thanks alot in advance.

make sure the engine idles smoothly and isn't 'tapping' loudly, drive it from cold and let it run a few minutes on a clean patch of concrete to check for any major leakage, make sure the heater/ a/c controls & fan all function. if it feels 'tight' over bumps [no big cluncks or rattles] and the oil's been changed often enough, those engines can easily run past 350k miles.

Thanks alot! I've worked on cars before, but only a few Hondas, and never actually a BMW. I've heard they run really well for a long time. I'll be able to check the car out this weekend. So far, it looks pretty clean. The person who's selling it states "no rust", though it looked a bit orange. Digital cameras are nothing to the human eye, so I'll get a better idea of it. For such high mileage, what would a bit more reasonable price be? Checking the bluebook value, I think it was booking about.. 870.00, though thats it's maximum value. Any idea on maybe a better estimated cost. The interior looked nice from the pictures I have, extremely nice for 20 years old now. No rips or anything, looked like the car sat fine and all. Just curious of opinions. 6-700 seems to be a bit more reasonable. Anyways, I'm excited to own this car, it really looks nice. Thanks alot!