I kinda agree with Kevin, to a degree. The single sided is cool, but really has been beaten to death, with Lambchops actually ditching his for the RSV Aprillia unit. Those are cool too, but now it seems to be the "norm" as far as trick updates go. Upside downs can be tossed right on with proper triple clamps on the front, but there you're already talking a grand to $1200 bucks without the motor.
My stance is this. If you liked his bike sooooo much back in the day, then that is the bike you should have. Original condition. Ask yourself some questions. Do you want to do the work yourself? If so, find out why the motor is locked up and learn to wrench on it yourself. It's great to have a bike that's trick, but much more so if you do all the work yourself. It seems you loved the original idea of the 900. Do you plan to drag race the bike and lose some of its genetically quick handling? If not, keep it stock length.
Bodywork can get expensive too, when you take into th fab to get other model stuff to fit, and if it's not painted that's another chunk of change.
I would suggest (only a suggestion, as its your bike and can do with as you see fit) that you keep it stock, get it in running, roadworthy shape, ride th snot out of it, then decide if you want to customize it. I'm pretty sure that after riding my "naked" RR around last year that I want a full faring on it in the near future. Good luck, and surely document it all with a build read and countless pictures. Here's mine: