Blitz told that they are buidling a GT-R for D1GP. Drivetrain conversion is done using Fairlady Z Z33 parts (i.e. gearbox, differentials and etc). What's fun: GT-R got a mated gearbox with differential - a transaxle one (ovlov style, lol) - and I don't know how they are going to manage the RWD layout. Probably mating the gearbox with the engine in the "normal" place, cutting the floorpan and making a small place for legs and pedals there. Also GT-R got sick electronics that even prevents installing wrong sized wheels. So they probably worked that out by removing all unexpectable sensors and setting up a new ECU. It's also most likely to have a nice turbo upgrade - as that's how Blitz started its business back in 1981. Anyway, would be fun to see how it slides, hehe.
The car would be stripped to a bare shell, and built from the ground up All the standard gubbins will be long gone!