1985 Mustang 2.3L

I have a 2.3L carburated engine, and have had the car parked for about 2 years, and when I put another engine in the compression was at 120-125, I just did another compression test and its sitting between 90-98, which is pretty low! I have good oil pressure, the engine doesn't seem to be burning oil but the question I have is there any easy way besides ripping the motor out to figure out why there would be low compression and what would be causing it. Trying to keep the engine alive without spending too much money on it because next year I'm converting it to a 5.0, so anybody can give me any solutions or recommendations that would be appreciated.

if you put a shot of oil into the cylinder before you check the compression and it comes up then you probably have ring wear. If it does not come up then its your valves.