I queried that too, I think it's probably a late '70s 2.7l engine, same engine family as the Carrera but not from a Carrera RS...the RS engines would all have had a serial 663xxxx.
A genuine, rebuilt, running RS engine would be worth about £18-20K alright, but you'd be daft to sell it and the square for €12k then
think it`s a 74 model can`t remember for sure. needs rebuilding too was pissing oil and the cylinder studs all need helicoils/case savers or whatever it is they need to keep them in the case
