My off-grid battery bank is made up of about a hundred used 12V Sonnenschein wheelchair batteries - each one 12V at about 38Ah I think, in a series/ parallel configuration to give me about 950Ah(nominal) @48V. Obviously not the same as what you're looking at, but the internal chemistry will be similar.
As long as they've been reasonably well charged when taken out of service (and haven't been abused/ worn out) you should have a chance, the self discharge rate is low enough that they can hold a useful charge for months if not longer. Load test them if you can.
If they've been sitting for an extended period at less than 2V (no load) they're probably not worth the effort.
I like their low maintenance, but not being able to equalise them like flooded cells is a bit of a pain as they age, you'll have to monitor variations between the cells from time to time. Mine are still going after more than 5 years.
Paul.