Good Heavens...
Yeah.
Are you after more Power/Volume.? Would be better to add a speaker cab.
You would be looking at replacing a Noval tube socket with an Octal socket on a PCB. That is just the beginning.
The OT primary will be wrong, and probably not "big" enough to take advantage of the 88.
Throw in 10 other things and you are back to what Jeremy says above.
good luck