Possibly a pro JBL type cinema sub?
Re old the 50s. These are mark 1 amps (you can see the thin amp handles) and potentially around the early 90s in terms of manufacture? So got to be at least 26-30 years old.
Basically if never serviced it will be needed now. Those mid domes, if anything like my experience, will be ‘tizzing’ (sounds like something metallic resonating badly) when you play music, say solo piano.
Granted solo piano might not be your thing but I am gently saying they could be like a classic saloon car ie you might need deep pockets and patience...factory turn around times are slow as they are generally always busy.
I waited 4 months for my new mid domes to come through which I only fitted this month. (Reconed ones from 2018, original 1996, failed. ATC policy is to replace for new, cut off around 2006 I think from memory).
And yes assuming you wanted to go full current spec got to be around £4K (assume amp rebuild, new tweeter, baffle, SL bass and mids) and the wait.