GIven the enjoyment you receive from your old and new LP’s, protect them and upgrade your cartridge and turntable. With budget considerations in mind, I would then look for a newer used integrated amplifier. Finally, you can upgrade your speakers. Not the order I normally do things but in your case it might make good sense.
You do not have to spend big bucks to put together a very musically satisfying system. Sort ought your priorities sound wise, do your research. When you ask for advice on this forum, you must be very specific as to exactly what you want a given piece of gear to do for you and at what price point. Otherwise, you will get a lot of random advice from members. Distinctly unproductive. (We all like to promote our favorite gear.) Good luck!