Dont mean to be a party pooper but I am just sorry that your not getting a Datsun,

Dont know all that much about BMWs but at a guess I would say they are going to be expensive to fix if anything serious goes wrong, and if its that old it may need fairly regular maintenance.

Yes it would be wise to check if the engine has seized.

Personally I wouldnt touch one with a barge pole.

my mum is gonna buy me a 1979 bmw 2 door sedan for my birthday its in great condition i love it i,m just wondering is there anything good to mod it with like turbo na or supercharge just wondering its runnin a carbi hopefully to be changed to injection will go awesome my only other concern is that the engine might have seized i will check it out before i buy it well sugetion will be helpfull