W124 300D Turbo, E30 M3, R5 Turbo II, RX-7, AE86, CRX Glasstop, DC2 Type R, VTR SP2...
Assuming it's a sound car and all the seller is saying is actually fact, that's a very interesting project. If it were where I am, I'd have bought it already!
6 Speed box should be a lot less prone to failure with the torque this car would be capable of. The Dieselmeken pump will also be very good. Engine is a good unit for tuning too.