XS400 (or machined RD400F) front wheel, FZR600 rotors
custom caliper brackets and custom fork brace, and I'm guessing they are TX500 lowers. That fork brace looks pretty clunky.
I'm thinking that might be Dr. Landau's old front end.
You can source your own used parts for cheaper IMHO. $500 is a lot of money for what's in the picture.
For example, ifyou use an FZR600 front end you don't need to make caliper brackets or a fork brace, but you do need axle spacers, rotor spacers, and you'll need to pick a solution for the steering stem (either modify the stem or add a frame tube extension).
Damon, you'll get a lot of opinions on here about upgrading front brakes. Most will tell you that the stock RD350/RD400 front end is more than enough, even for racing. The dual-disc upgrade adds weight and extra braking power that may not even be necessary. It's mostly for the "bling factor". There are some threads on this site discussing the pros/cons of front brake upgrades. If you're looking to make your bike custom with different front brakes there are quite a few threads on here about grafting other forks/brakes onto RDs.