Here you see two 5/8" holes ...
but I need 20mm holes ...
Having finally filed the top hole out large enough to fit the 20mm bolt ... I am pondering the effort required to file out the other one. I WILL do it ... eventually. But I think I'd rather go get a haircut right now ...
If the option was to go to the dentist ... I'd start filing again. It really takes time to do this, my T-shirt soaked in sweat, I come home all filthy and my wife wants to know what I've been doing ... just filing ...