Best bet to go with the updated swingarm and front forks is to get a complete donor bike. It's the little bits that will drive you nuts and end up past time on the build. Plus for points, the wheels will match, and the suspension/tires size/brakes will do even better together.
Most any bike will do, but the Suzuki GSXR stuff is top notch and plentiful. I personally would go with a ZRX setup for you, it has dual shocks (rare nowdays)so there is a little bit less welding involved. You still will have to become very good friends with a machinist, and feed him $$$ well.
(Interesting note to self: what other modern bikes ran dual shocks, for donor purposes. Hmmm.)
Actually, I would go all out with what you have, and save on the fab. Just pick a way to go with it: cafe, drag race, road race, or wild chopper. Clipons are available for your forks, as are apehangers. Custom seat cowls are relatively easy and cheap to build. Paint jobs can be expensive, but most $$$ is in the prep work. Learn to do prep right, talk to the painter, do what he wants you to do the first time, and money will be well saved.
My build (other than the paint):
Change your headlight (I'd go with a bullet style like on the 82GPZ's), get some drilled discs, ditch the mirrors and the turn signals, install a bar end mirror on your clipons, build some rearsets, build a solo seat and a cowl, ditch the front and rear chrome fenders and measure something up for the front fender (84-85TurboGPZ fender comes to mind). Vance and Hines pipe for looks, Pirelli Sport Demons for the name and the look of the tread, a steering damper and fork brace, and then bracing up the stock arm.
That would be my start for a bike build off. I could have it finished and worked out in half the time of the other way, look alot cooler, and work on the details that make a bike stand out.
84 GPZ750. Modded with stock Kawasaki parts: ZR-7 shock, ZX-6 coils, GPZ1100 throttle, EN454 brake, GPZ900 fuse box, etc. and non stock: Ken Sears mirrors, K&N filter, Pirelli Sport Demons.