Even if it is cyl & cyl, it will do fine on close birds.
There should be an additional marking -- the barrel weight. It should look something like 1K123. That is the barrel weight in kilograms. It was done at the proof house after it passed proof. It is the Belgian method to let you know if the barrels have been tinkered with. So all you need is a scale...
I was thinking about that chamber marking of 65mm. I seem to recall that the 28ga is not legal for hunting in Belgium. One of the reasons you do not see many.
My guess on the left trigger is that it just needs a good cleaning. Perhaps some light stoning.
For the price you paid, you got a little gem.
Pete
