Yes it would be absolute blasphemy to drill holes in that rifle but.........

I'm all for SHOOTING these fine rifles rather than just admiring them and I know exactly what you are going through regarding your eyesight.

I reckon so long as the new sights are in keeping with the rest of the rifle and are fitted neatly and professionally, go for it.
After all, it sounds like you intend taking the rifle out into some excellant country and after some serious game.
From what I've read, Bell was a hunter not a collector so I think he'd be all for it!

Also, if you don't buy it and give it a good home, how do you know that the guy who does buy it doesn't let the thing go rusty in a gun bag or that it suffers some other fate far worse than fitting a peep or scope!