You know, I don't think that doing up a section of the B&SR is still impossible... Just made more difficult without authentic equipment. 8 isn't doing anything, but would be expensive to run, and who knows what MNGRR wants to do with her (although, someone else paying to move a few pieces and take them off their hands might make their moving costs to Grey go down)...
Assuming that you chose two points on the line where there are things to do, it could be used as actual transportation in addition to serving as a museum. Just price it right and on operating days, make the schedule convenient for the traveling public.
Obviously there is only x-amount of narrow gauge equipment to go around, and infrastructure to maintain and house at least one locomotive and two coaches would be needed first and foremost... The section to be restored could be cleared for a trail first, making getting tracks in somewhat easier... Just move the trail once the tracks go in. Then there's just the fact of getting funding to cover supplies and movement of equipment, capital to start operations, etc.
