No idea, but are you sure that the emitter spacing on the linked MCPCB matches those on the optics you have? It looks like the MCPCB is intended for use with the manufacturers own optics.
Something on RS told me they should, but I’ll double check before buying. LED4Power got back to me, they have 6 LED PCBs (hence why I missed them) for the optics, in 3535 and 4040. Centre LED is missing to allow for wires.
Just received another email saying they will have full C8 conversion kits in soon