Butchered injector threads

[octanematt]

Best way to fix this? It came out pretty easy using my Torx socket as I didn't realize someone had changed it out. So it wasn't that tight. And there was some sizeable metallic debris in the hole after I got the bolt out. Doesn't seem like it was doing much and the injector seems pretty stuck. In fact it look like it might be held in with JB weld...

My thought was to get the injector out and then properly fix the hole so I can use the proper sized (metric) bolt rather than the 1/4" one that was kind of in there.

How big can I drill the hole to effect the repair??