My 2c worth Craig, is keep the R8N as original and unmolested as possible. As a desirable, limited run, it will have the most chance of holding its value, and a bit of that unobtainable "Honda prestige" (read into that whatyou will....).

Of the other two, keep the RVF front end, as per your comment re its difficulty to obtain there, for your track bike. Depending on the setup, it'll allow you to run wider rims for a greater variety of rubber. Fairings won't matter much, and feep all the hrc bits to play with.

If you must, sell the other (titled?) one - you should be able to find a buyer for an original(ish) condition MC21.