Anytime you come across a huge hoard like that its bound to be a bit strange, especially when they start running out of room to keep things.
I've had houses, barns, chicken coops, and school buses filled with parts that I cleaned out over the years.
The biggest challenge is moving it all and then getting it all sorted and organized so its of some use.
I find that about half of most hauls like that are dead items in most cases but once in a while you get surprised.
The older the collector, generally the older the items you find. When your talking 40's and 50's items, your likely looking at collections that started 60 years ago or more so you have no idea what you could find in there.
That hub shell reminds me of a late 40's Raleigh I had here a few years ago, it had the same color paint, same arched Made in England.
Maybe the guy had some idea of reusing the bb shell? If it was loose, he obviously had the tools and means to take it apart yet he saved it whole.
Block chains like that were usually racing chains but that one does look narrower than most I've seen.
One place I cleaned out up in NY had a full roll of 1" pitch x 3/16" chain. I sold the whole role to a collector in the midwest.
Old skip tooth or 1in pitch chain is getting hard to find, so that alone is likely worth your time, plus all the SA parts. They don't make any of that stuff anymore so its only going to get rarer.
I cleaned out a place 16 years ago that was packed up like that, the guy had his house, garage, and barn stuffed to the rafters. It was mostly bikes and old parts but I did manage to turn a small profit in the end with the few new old stock parts and a bunch of vintage carbide headlights and ooga horns. Each time I swore it was the last big load but they keep coming. I got a guy with a huge 'collection' waiting for me to get the time to go check it out. The last time I was there he was skinning chipmunks and squirrels he caught in various traps around his property. At that time he had bikes, parts and tools stored all over his wooded property. He had old campers, trucks, buses, cars, and outhouses packed with old bike parts. He was living in an old slide in camper body because he had filled his house with bike parts. An old bread truck was his workshop. Back then he didn't want to let anything go, but he had dozens of rod brake bikes, and quite a few prewar wood rim bikes in decent condition. He was older, likely in his 70's or so.
Now, anyone who lives with greasy bike parts all over the house with the smell of grease and parts washer fluid in the house makes for a special type of strange. Rest assured though its not likely to be the last, and its not likely to be the strangest place you've seen. There's always one just a bit worse than the last out there waiting to be found. There's always one just a bit stranger right down the road.