Cleaned the mock caliper adaptor up this morning & tried it for size. Fits perfectly so that was a relief, I didn't fancy making another !!

I tried it on the right-hand side too & it fits that side too although I did notice the required spacers that would be needed to centralise the caliper over the disc varied between the two sides. The left-hand side would need spacers around 8mm while the right-hand side would be around 3mm. The final adaptors will be machined to suit each side so I won't bee using spacers anyway, but I'll be making some just so I know exactly how thick the adaptors need to be in that area.
The ABS sensor mount seems to work OK too & the cable looks to be plenty long enough to reach the headlight, (where it connects apparently).
Obviously this side's adaptor will not have that lower mount for the ABS sensor.
The difference in required spacers can be seen in the two photos below, this is the left-hand side.
And this is the right-hand side.
When I looked, the caliper mounting boss on the two lower forks legs is in a different position slightly, hence the off-set difference. I did wonder where the difference was because I know the wheel is dead central in the forks/yokes.
The ABS sensor mount should work well too, although the gap is a bit big at the moment !, but a suitable spacer will soon cure that problem. I think is should be around 1mm maximum, but I'll check my workshop manual. I'll also be able to mount a P-clip to the back of that adaptor, which will hold the sensor cable securely & stop it flapping about. I will have to re-position some or all of the cable grommets, but that won't be a problem.