[AI2V]

I don't really see any major obstacles here. I would guess that the original tube sockets were leaky and intermittent (often are for that vintage) and they were simply replaced with the more modern and reliable octal sockets and tubes. It's something I've done on junkers when I ran into repeated socket failures in a single radio.

Simply replace the sockets with the originals. Mark the wires as you take them off as to plate, G1, SG, or whatever and reconnect them to the replacement socket. As for the eye tube, just disconnect it.

A while back I worked on a Philco 19 junker that drove me nuts with sockets that would arc or just couldn't be made reliable; one by one these sockets were replaced with octals until the entire radio had nothing but octals. It works beautifully now and I would never get rid of it. (I know, I know- what about the tech in the future who services it? It's not my concern.) The chassis is marked for the new tube types.

Look at your 90 as an opportunity to better your skills in tube electronics ; swapping to different tubes isn't that difficult usually.