Yuuuuur from the research I've done:
My OEM 318 is 22.2 / 20.6
330 is 23.8 / 22.2
E46 M3 is 25 / 20 with MK20 ABS and 25 / 22 with the MK60 (these look like approximate sizes, likely 1" in reality etc)
So I'll likely have a look around once I know what sort of front to rear size ratio will work best for my setup. Have located TRW M3 for a non insane price
Printed off a rotor hat so i can do more fitment mockups / validation, only just fit on my printer bed and took about 16 hours !!
I then added a portion of the rotor and glued them together ... too keen to get it glued up and neglected to ensure it was nice an square so may turn out to be of limited use 😕 Might do another one for the other side over the weekend and ensure i do it properly.
Picked up the result of my thinking cap time also and am really pleased with how these worked. This was to validate more accurately (than my 3D printed 'jig') what i had measured with my laser level. What I'm measuring here are the offset front to back as well as depth of the caliper mounting holes in the knuckle vs the centre. Attached is my high tech engineering drawing if anybody wants to replicate 😆
Worked out really well, and proved the 3D printed jig was only about 0.2mm out front to back !! From memory there was a previous 1mm variation between the laser measurements and the 3D printed jig also. Shout out to James Simpson Engineering who turned these for a very reasonable in 2024 $40.
I should point out that while the 3D printed jig was a good fit when on the car it was essentially impossible to measure the 'as built' dimensions of the plastic part. I'm being pretty particular here as I'm in no hurry.