The 3.0 cdti lump from the Vectra would be an interesting project, but would require some headscratching to fit a rwd car, although this then raises the possibility of twin turbos
It was available in the preface Vectra C/ Signum half CAN cars so shouldn't be too hard to get working, to make it fit RWD just turn the engine in the same way the V6 petrol (basic lump) is as used in Omega/ Vectra.
However its not a tuneable engine iirc in preface cars its around 184bhp, facelift its 197bhp (or the other way round) and the few that have tried to tune it have had lots of issues fairly quickly afterwards!
It you want twin turbo then there is the 9-5/ Insiginia 2ltr lump that has twin turbos and 190bhp, which apart from the CAN issues could be a good place to start
But to be honest performance diesel is an oxymoron, you want a powerful, big engined, fast, tunable car, buy a petrol with forced induction :-)