Thanks for the replies everyone. The car is slightly out of alignment and I'm aware I'll have to replace the wheel ASAP, but that's (I think) a relatively simple fix. The panel basically collapsed into the wheelwell. I'll attach a pic of the damage. As I said, the door doesn't match and that's exactly why: the original one took a majority of the impact. Hard to believe, but the frame is straight as an arrow nonetheless.
I understand your collective concern about buying from a friend... but he and I are operating on the premise that the car will need lots of TLC to get back to where it should be, and that he simply doesn't have the time or knowhow. He is the second owner, the first being a middle-aged man with a complete set of maintenance records, which I have complete access to.
PS. I bought my 240sx from a friend, and despite replacing the clutch hydrolics, all the fluids, all the
EDIT: [brake] rotors and a head gasket, he and I are still close... and this is on my daily driver!