Restoration or butcher project?

If there is only 400 of them made then there are likely a Holden car collector that would have interest in a well restored vehicle.

Depends what you want to do with it. Drive it or sell it.

Driving it would likely be expensive unless you gutted the engine and put in more cost effective fuel consumption. Gutting the engine and replacing it with something else would likely spoil the car in the eyes of some Holden collector. Maybe there are some Holden parts that could be put into it to replace the engine but IMO Holden cars are generally not designed for economical driving.

Don't know a great deal about engines or cars. Just that collectors do like well restored vehicles. Don't know how popular the Nitron is or was. If it was a sought after car in its day then you may do OK restoring it.

I am sort of stating the obvious really. In the end it will boil down to what you personally want to do. Whatever you put into it will get reflected into the value of the car. I would investigate what parts Holden has to restore it. Even though Holden will be closing down operations there are lots of Holden parts floating around that you can likely pick up cheap if you find the right sort of spare parts guy. Finding that Holden spare parts guy is going to answer your question most of all IMO.

The condition of the car exterior looks good so that can be restored fairly economically. That will be your selling item and if it backed up by a Holden engine and internal workings that are economical and perform well, then I reckon you could get a decent return.

That thing does not even look like an American car. It appears to be already butchered.