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I think he concluded it was not practical to drill additional/larger holes for more water to get to the bushing. BUT, I'm not totally sure of that.
I didn't pay a lot of attention because my engine already had the lower unit with the larger holes.
This is just an opinion, and hopefully others will jump in with a better perspective.
I would just leave it alone for the season. Water will just go in and out of that hole and may even provide some extra cooling to the bushing. Then, when you haul the boat, find a master welder who has lots of experience with aluminum castings. He could probably put a good patch on it. Then clean it up really well, primer it with a primer made for aluminum - probably at least two coats (three would be better) then paint it and clear coat it with several thin layers.