In my opinion the L78 nova sounds nice. Most have replacement engines anyways. For paper work there are a few good men on this site for that deal. Just fly Marlin where the car is to verify it. Paper work has only become important since the non car guys got into the hobby. Sooner or later most cars identify themselves. A real L78 nova with credentials from people like Marlin, MacNeish, Wayne Bushy or Schonye along with your gut feeling would be good for me. I don't think you can go wrong.
