Original wedge head cabs were made of poplar and often planked, using several pieces glued for each side. Call me a purist but I believe there is an acoustic element to the old EMs and replacing original construction with different materials other than what was originally used or slathering bonds on cabinet elements can have a detrimental effect, agreed, this is an extreme approach. The older EM wedge heads used a cheaper layered wood and are problematic, air pockets etc. I have pics of some wood repairs on FB https://www.facebook.com/Preservation-Pinball-and-Paint-383113651705319/?ref=bookmarks
Good luck either way.