Welcome to the forum Sam.
Personally I wouldn't bother wasting my time or efforts on repair of existing alarm panel.
I'm guessing you already got quotes to update panel and set you up with a new service.
That said personally I would remove the panel and replace it.
I would also validate end to end wiring and loops and replace all of the sensors, consoles, et al.
This would be the least expensive piece of the endeavor.
The most expensive piece of your endeavor would be the time involved checking the wires, loops et.
The wiring is probably just fine. Depending on how the sensors were wired you may have many loops.
BTW I am using still today much Moose / Elk stuff dating back to the 1980's / 90's and have to date never had an issue with hardware that I purchased.
Today I have two HAI Omnipro panels installed in two homes; one now for over 10 years with no issues and the other one some 6 years with no issues.
The above noted many users on this forum have Elk panels installed over a similiar time frame and have had no issues with said panels.