Only with MAJOR whittling. The engine bearers are solid hardwood, 3/8" thick that glue about 2" behind the firewall, all the way to the nose plate. You COULD remove them, but it would be major roto-zip tool kinda work, and would take some patience. However, it would take a lot of nose weight out, meaning that whatever mount you went back with would probably not appreciably affect the overall balance.

Question is - What mount? The firewall is a bit narrow, and short for a Hyde-type (I think, although I don't know their mounting dimension on the 90 size)
Gator would work, maybe, but it's pretty wide. You could remove some stock by cutting it in half vertically and removing some of the backplate mounting material, but how much would be based on the engine you choose.