Did you have any joy?
Can you even buy 10mm hub centric?
I've checked Tamar and Watfields Engineering along with the the usual suspects and I can't find them. I'm thinking that maybe the lip on the hub is greater than 10mm so you only need shim spacers but I'm wondering if the wheel will only just sit on the hub lip which doesn't sound ideal to me.
I don't think it'll work but no harm in asking or trying to be sure. If he machines the back then the spacers lip will stop the spacer sitting flush with the hub for sure and if he machines the front then I think the spacers lip will fall off.
All this time I thought my YTS in mechanical engineering was waste of time 'cause I preferred coding BASIC on my Spectrum 48k then I come across this dilemma and it all comes flooding back.