dunno if it's of any use Von...but I done a front end swap on my old zzr1100. I put on a ZX9 front end and the same as you, the prefered method of sorting the yoke/stem problem was to have a new one machined.

I found out the stem of the 9 & the 11 were the same diameter it was just the length of the stem on the 9 was too short.

Perfomoto in Tottenham came to my rescue and swapped the 11 & 9 stems over....fuck knows how but they only charged me £80 quid I think it was and bob you aunty's live in lover, everything fitted lovely like.

So just an idea to chuck in, if you can find a stem that fits the headstock that has the incorrect yokes, you may be able to get em swapped over.