I think it might work. That 3mm stock plate thickness is the "new" spec for them but most used ones I've checked still measure at that. 6 plates @ 3mm would "fill" 18mm of space. 7 Alto plates @ 2.5mm would fill 17.5mm of space. But, the wear limit on the stock plates is 2.7mm, so 6 worn to the limit would "fill" 16.2mm. The clutch would probably still be functioning (although maybe slipping) at that wear limit stack height, so it just stands to reason it would function fine with a 17.5mm stack height.