Update on the progress, once I got it cleaned up and back together, I found that the bolt would not remain in the cocked position when closing it.
Also it would not extract/eject a cartridge when fed in by hand.
I ordered a trigger, sear and a spring set off a guy on eBay and it arrived today.
I installed it and tested the rifle and it now stays cocked, loads, fires and ejects as it should.
Next question is the condition inside the barrel and whether it will group reasonably or patterns like a shotgun, to be continued…