Tod I have the Mitas H-02 350x19 on several of my bikes and done 1000's of miles on them over many years. They are not a large 350 tyre compared to some others and will fit easily on an M20. There is no physical difference between an M20 and M21 anyway. Ron
You lot are spoiled for choice
when available I fit a 325 front and a 350/400 rear
I never understand metric tyres but I think a 90/90 fits but the 90/100 & 100/100 does not
And yes WM3 front & back