Boring Out A 700 Twin

Right now I know wiseco makes a big bore kit for it that takes the bore out to I believe 83mm. Problem is I seized one of my cylinders that had this big bore kit done. It is iron sleeved and bored out to 83mm. I would not like to buy new cylinders if at all possible. So i was wondering if I could get them bored out to 84mm and throw a stock 800 piston in it. It is only an extra millimeter. They guys at the shop told me I couldn't, but I like to try things myself. I dont see that millimeter making that big of a difference.
Or would a stock 800 cylinder fit on my 700 twin crank case? what if I got 2 800 cylinders. Would those fit on my crank? If I have to buy new cylinders I might as well go bigger.

Thanks
Carl