The suggestion to remove the keybed, or key table, is perfectly sound.
I have done this with a number of Stecks for removal purposes where
clearances were tight.

I have one word of warning: the piano will become violently back heavy
as a result.  Be extremely careful.

Roger Waring - The Pianola Workshop
Solihull, West Midlands, UK
http://www.pianola.co.uk/