The little Williams peep used on the Buffalo Classic (used to be avail. from H&R but Brownells for sure) will
screw right on if you remove the scope rail. A ramp front like the Williams with a one screw mount would be easy to mount and they use the replaceable sights to get you to the right height.
If you must keep the scope rail on you can dovetail the very front of the rail for a low open sight and still be able to pop the scope on/off. Again, you will need the front ramp and an appropriate height front sight (probably pretty tall, though) to -0- in.
Or, you can mount the Williams Guide open rear sight (need to D/T 2 holes) on the barrel.
BTW, a friend used the peep on his open sight equiped 22 Hornet Handi and it worked OK with the factory cheapie front (may be avail.?) but the Williams front would be nicer.