you could just have the hats for the ra-r rotors redrilled to 5x100pcd between the existing holes.

I have seen some after market replacement rotors for the brembo equipped gdb's with both the 100 and 114.3 pcd patterns.
(I think they were a well known Japanese brand, the name eludes me at the moment.)

there should not be any strength issues with redrilling the hats as many wheels have a void area on the back of the mounting flange between the mounting holes, and therefore have no clamping affect holding the hats to the hubs.
(an example of such wheels would be the ra-r wheels themselves).

I make this suggestion as it would be unlikely for you to find a hat with 114.3 pcd which has the correct offset (to mount the rotor in the right position in relation to the hub),
the correct pcd and bolt spacing to attach the rotor to, and the correct sized centre bore to locate properly on the hub.

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