Cleaning the original is the best way to go. As for the compression, if its been sitting 25 years it could be stuck rings, put some PB blaster or whatever your preferred penetrating oil is down the cylinder and let it soak for a couple days, get it running, warning it will smoke like crazy burning that stuff out so don't panic, and after running it for a while see what the compression is then. That is if it runs, could be a sticky valve not closing all the way to, will just have to see after getting a working carb on it. But 60 psi is pretty darn low.
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1984 Honda ATC200ES "Big Red"
1982 ATC200E "Hondie"
1988 TRX300FW "Project Quad" Still in progress....