I've had a look thru my 'assorted box of bits' and have 6 brackets for the M80 sight.

3 different types.
Just to confirm I've got the correct ones - the fixing holes centre to centre spacing look to be 19mm (3/4")

If interested make me an offer for any number (1 to 6) If you are not interested, no problem at least you now know what you are looking for.