All fitted now, horn works + no air bag light. It turns out that early model zeds have a single loom to the air bag, and thus only need one resistor - whilst later model zeds have two and need two resistors. If you're buying Momo be careful because you only get one resistor in the hub kit, bit late to find out when your steering wheel is off! - fortunately i only needed one . To be fair i called Momo and got all the answers i needed off the first guy i spoke to, good customer service as least.
Ian i think you were right with a 350mm wheel, that's what i bought and it feels spot on - oh and you can still see all of the dials, any smaller and you probably wouldn't
Few pics fitted..
Need to do a few journeys to see if i need to adjust the reach, but for now i'm very happy