for ease of use i would just jb weld a bolt in there and smooth it out afterwards. its not like its weight bearing or anything. if you want to weld it bring it to Timmons Machine just to the left of the shop that i work at (that you came to). Hes a master fabricator.
I can have it tig welded for you. I would just need to know when and where your at and getting the tumblers. Same guy that welded Trevors tumblers (on his former-STi) would do it for you. Let me know what you have decided.