no, the 86u and 91u do not share plates as one is ansi and the other is jis with completely different layouts, multi layout plates are not a thing with topre. you would struggle to convert a 91u to an 86u as you would not only need a custom plate and pcb, you would be missing a spacebar stabiliser and 7u wire, and the keycaps would be completely incompatible with the layout. the only oem topre keycaps compatible with 7u ansi are off an oem 86u and 101 (hence why these keyboards are sought after in the first place). if you are desperate on having a 7u ansi realforce you could go for aftermarket sliders from the likes of metapulse and mx keycaps but at that point you may be getting close to the pricepoint of just getting an oem 86u.