[tccrab]

Buying cars as an investment can be a hit or miss type of thing. i find it's a general rule that modified cars tend to have a much smaller audience than un-modified cars, and as such tend to resale at prices much less than the cost of the mod done to the car.
Notable exceptions are cars modified by big name companies such as Calloway or Lingenfelter; or well known specialty shops such as Haibec or Doug Rippey.
Your '90 with a '95 nose and body trim would likely send a NCRS kind of buyer into convulsions. Their first thought would probably be to ask what damage was done to the cars original body panels to warrant replacing them with *shudder* the wrong parts. These are the same people that berate the owners of '63 split window coupes who opted to cut out the middle section of the of the rear window and replace the split window with a '64 style one piece window. If you've ever sat in the drivers seat of a split window and looked through the rear view mirror you would understand completely why they did it. Trouble is, the modded '63 wont command nearly the resale value as an un-modded one.
The same thinking will apply to your car, first it'll raise questions and then the price will drop.
Lucky for you, the nose pieces are not ZR1 specific, so theres lots available in the resale market. What's going to bite you in the butt is the body trim from the doors back and around the rear bumper, and the rear bumper fascia itself. It's 1990 only and it's going to be hard to find and it wont be cheap.