You are partly correct.
To fit the standard rear brake mounting plate albeit with a little bit of filing, your options are:
1. Standard Rear caliper (including Fazer 400 version)
2. 2001-05 FZS1000
3. XJR1300 bluespot/silverspot (can't remember years)
Other rear calipers will fit with an appropriate rear brake mounting plate and rear brake hose. For example, with the TRX850's mounting plate, you can fit:
1. TRX850
2. YZF750
3. YZF Thunderace
You might notice that these calipers all look very similar...because they are.
Mounting plates for the YZF750 and Thunderace are not suitable however, because their rear wheel spindles have a larger diameter, whereas the TRX850 shares the same spindle diameter as the Fazer's.
I have a Thunderace caliper fitted to my own with a TRX850 mounting plate