about he roraty
well my bro attempted a turbo 12a into a 120y coupe. He got it to fit, but he had problems with the steering box bieng in the way nad the driveline angles were really bad.
The used a series one 5 speed manual, which I still have in my shed if you want it. he eventuallly gave to project away and sold everything and bought a 4wd. still though, it use to pull wheel stands on the street. Just put the front tyres just before a speed hump and then dump it and the bottom of the boot used to hit bitumin!! Funny as, but death on wheels. He didnt bother to modify anyting else. just droped the motor in and drove it for about 3 months before ditching it.
It was the driveline angles and the steering box that were the biggest problems in that saga.