Without pics it's tough to say, we don't even know if you actually identified the bike correctly.
UO-8 and P8 variants ready-to-ride in my area usually sell for $125-$175 depending on the condition so you're unlikely to net much money on resale. I've seen some in perfectly-mint, fully torn-down and rebuilt from ground up sell as high as $250, but in a very desirable color (green/purple/orange draw more $$) and with no kickstand damage.
The UO-8 was an underrated bike, classy, albeit heavy. If it's in great shape, it's totally worth keeping. Upgraded with alloy wheels you'll shave a pound or three and they become more rideable (save the old wheels). For less than $100 in parts you can have a practically new, fully-serviced bike if you have the knowledge and tools to do the work.