Peter
I do not think i am a heavy hitter, maybe a light to medium hitter, but here goes. There are gimei swords that are worth restoring. I have a sword that is not mumei that was gimei. The mei was removed, it was polished and passed Juyo. That being said - the blade is everything, if it is good workmanship the mei can be removed. Many swords made in early Showa had "big" names, so if it is a Showa oil tempered blade then not worth it. Best to leave it as is and research the blade, try and show it to a few collectors and listen to what they say then decide