My 500 project was originally going to be a TZR2503MA framed bike.
I've since seen the error in my ways, and I'm now going to use a Mick Costin framed bike. I pick the frame up next week.
Many of you will probably want to hang me up for this, but heres the bike as I bought it a year or so ago

So far, the bits I have collected for it are:
TZR USD forks
Marvic racing wheels

RGV banana swinger
RGV WhitePower shock with remote res (although Mick tells me I may not be able to use this with his frame due to its length)
GXSR 750 4 pot calipers
The part that is sure to spark plenty of debate is the fuel injection.
I've built a megasquirt unit (http://www.megasquirt.info) for this, and bought the throttle body injection from a GPZ1100 (TBI, fuel pump, TPS).
The megasquirt is a programmable unit using a laptop, palm pilot etc, and can also control ignition with an upgrade. The newer version does both straight out of the box.
Plenty of people have said it wont work - I dont yet see why it wont. Someone in france had done it years ago with a much more basic injection system than the megasquirt. Especially with TBI, they are basically like a carby, with the injectors being in the throttle body.
In any case, the whole setup has cost me less than carbs (under AU$500), and the megasquirt is universal, so I can use it for something else if it doesnt work.
The engine will have some minor work done to it. Mick Abbey in England has just finished tweaking my barrels, and they should arrive home with my sister next month. I will be using RZ350 reed blocks.
I have a webpage here:
https://www.winsto.net/projects/index.php?blog=5
It will be updated as I go. It hasnt been updated for a LONG time because I've been waiting almost 12 months for the frame.