A limo conversion shop could s-t-r-e-t-c-h your 2 seater car in order to make room for the rear seats. It would cost a small fortune and it wouldn't be worth it. There's two other z31 installation options that people occasionally ask about: all wheel drive and air bags. Not impossible to do but next to impossible.
To each his own ****!!!! If he wants to put on his apron and play "butcher" with a Z like that, I'll take it off his hands at a reasonable figure and treat the car with the respect it deserves. What was that saying AZ_ZBUM? "Common sense just isn't that common anymore". And...what's the Mercedes got to do with anything?