That's probably the fastest way. I'm not sure how to PM here, or if I can(hey look a banner about it). Poking some more your profile lists a website, if you can email from that domain I can be reached at my username at gmail. I think that will probably establish authenticity fairly well.
Given...
I happen to have a packet of disks from this model if you're still looking. There's a couple msdos 3.1 disks, but also a disk labeled 'diagnostics'. Also an empty sleeve :-(
I don't have a 5.25 to verify or image them with though. But if you think the diagnostics disk is what you're looking for...