Not exactly the same, but I did pretty much what you're talking about on an '86 Schwinn Passage that I Frenchified a few years ago. If you can reach over far enough to use the downtube shifters, then it isn't much trouble to reach for the bell instead.
I don't remember exactly what was involved, but I think I just disassembled the Suzue "Crane" bell, and drilled a hole in the little flat section between the bell mount and the curved part designed to clamp onto a stem or handlebar, then cut off the excess. I was able to just sandwich it on top of the right downtube cable stop, reusing the screw that holds the stop to the boss. A bit of blue Loctite, and I never had any trouble with it.
In fairness, the bell never got a ton of use, but it wasn't due to ergonomics. It wasn't any trouble to reach for a quick ding -- I'm just not much of a bell ringer by nature. The trails around here aren't so crowded that I can't just slow a bit, and find a way to pass with ample room and a simple "Hello" or "How's it going?" as I overtake them just slightly faster. My bells pretty much just get used on walkers / joggers with earbuds, or dog walkers, more so I don't surprise the dogs.
Pic:
It's now living happily in Connecticut, where I imagine it gets taken on spirited rides, and enjoys rambling rides to the beach. :-)