Chris,
Exactly like mine save that your incoming one looks to have a leaf sights and ladder sight combo sight. Mine is just 3 leaf sights, 1 standing & 2 folding.
Yes to the large swinging safety. If I remember correctly once the breech block is removed the safety unwinds counter clockwise for further disassembly.
Apparently not many produced and even fewer known examples. Mine is Tranter #242

Be interested to see if it is .500/.450 #1 Eley (Express) like mine.
- Mike