Well, after being absent from the site after so long...
I thought I would chime in on this.
Lovely car you have Josh! Amazing that most of the original equipment is still there. I would have to say though, I love that maroon colour that is on there now, if I were you, I would match it and have it sprayed that colour, just my opinion.
As for the engine, I understand the idea of simplicity and reliability with the Nissan engine but, I would put perhaps an M104 in there or something from a mid 90's Mercedes, parts are still plentiful for those, although, if I still had the original engine and drive line I would have most defiantly used that.
But hey, its your car to experiment with! I can't wait to see your finished product and when you have time, please keep this updated with photos if you can, I would love to see how its coming along.