Larry,
Drilling after you weld the notch might not be the best approach, as you won't be able to get the drill to follow the original hole if you have any weld metal sticking inside the original bore dimensions. It will make the drill take more off the good side of the hole. Unless you have a machine shop renew the bore with a proper tool (probably a fly cutter on a lathe after centering it on the original hole), you'll probably wind up with an oversize or out of position hole. You might get away with welding the notch up if you grind the excess with a dremel tool being careful not to touch the original bushing hole. I'd do that and then use some JB weld to fill any remaining gap.
Or for that matter, just install your new bushing and fill the gap with JB weld. The possibility of you needing to replace the bushing in the next 50 years is slim to none. You may need to use an expoy filler that's a bit thicker than JB weld, as I've found it prone to sag a bit before it hardens. I'd suggest something like PC7.
