I'd either avoid screw in chokes or loctite them in, changing chokes just doesn't seem to work with these types of guns IME.
Even a custom made fixed block that's been braised or similar and then opened up as a choke would be good, if more expensive and much more hastle, I'd personally leave it cylinder and get it jug choked for my money.
I'd avoid a big front sight and put a larger bead on it with a low more open type rear sight.
You don't want rifle sights so much as accuracy isn't as good as with a rifle and speed is a big factor, even a ghost ring would work better.

I've had great success with a 1-4 scope, still a favourite despite it being no good for small game.

Keep it simple and keep it fast, it's a gun for running game, not a gun for precision stationary shots.