Best you measure the frame mounts very carefully - as far as I know (not usually much) the 748R's have a completely different frame to all other 748's to accomodate a larger airbox - 13 litres I think. Whether this effects sub-frame mounts I don't know but maybe measure just to make sure. Seems a bit strange to me someone would bother to mount a BIP sub-frame onto an R - kind of defeats the object.
Mood: Finally gotten over the 748R getting stolen thing. Actually, no i haven't !
I would check carefully that the BP subframe is not an indicator to a serious mishap by a previous owner. I have both bought and sold R subframes for 748's before, about £150 should get you one. Don't even ask about buying new. For what its worth all the subframe mounting holes are comparible.
Only 748 SP, 748 SPS or 748R/RS will fit as the 916,996 series sps's have the larger ECU so the mountings are different.
the 996r sub frame doesnt mount the ECU;- which sits on the right hand engine side, so doesnt have the front ECU mount which also mount the seat bracket on a 998rs