126 500sel - 280 conversion?

[benz831]

ok, if the motor is trashed in my 1984 500sel, is it possible to put a 280 6 cyl dohc motor in instead as a replacement? If so, will it need a different tranny or motor mounts? The donor motor is coming out of a 1977 116
280sel, it currently has an automatic tranny in both cars. I know they made a 126 model with a 280 motor in it, the same motor in fact, I also have a 4 speed manual tranny in a w116 , and am wondering if that would fit in the 126 as well , if I do decide to convert motors. any and all comments and suggestions welcomed and appreciated.
1984 500sel 300K
1977 300D 386K
1978 280sel 200K
1978 280sel 115K