to calculate proper bridge radius (in compound radius situations) use this radius calculator spreadsheet
to measure the radius of your fingerboard, and under the strings (actual bridge radius) stew mac under string radius guages or for just the fingerboard, the notched stainless steel ones might be a bit more durable.
to get the correct radius at the bridge use shim stock, available from universal jems, or all parts or just pick up a variety pack from your hardware store and cut the square's yourself.
Original floyd's are 12"radius on their own, but most of them come assembled with a 0.01" peice of metal running under the ADGB saddles to make it roughly a 10" radius.
If you want to be completely **** about it, take off the metal plate, install the bridge, use the under string radius guages to measure the exact radius you get, use the calculator to find out the exact shim size you need under the saddles, cut and install it, reinstall, recheck with the under string guages. Now hope you sanded the nut area to exactly 10"