I ended up filing the slots on my SG cuz my replacements were bigger. It really was much easier than expected. I didn't measure or anything...just started filing away, checking the progress along the way with the new tuners. I spent maybe $4 on that job total, and that's only because I didn't have the router and file. Of course tuners that fit exactly would be ideal, but if that's not the case, then don't be too intimidated by the job.

Here's what I used: Bastard File and handheld router.