86 TRX350 advice and help

Hello I just finally registered after lurking around and reading for a month or 2. This is a great forum!!
I'm hoping for some insight or advice on my 86 TRX350. I was given this bike after it sat inside at my work for a year. Story is that it ran, but shut off. I figured out the ignition switch was bad. Ordered a new one (Honda OE) and replaced it. Got it running off carb cleaner and decided to get a carb kit and drain the old gas. The carb had been replaced with what I believe to be a newer model one since the throttle cable wouldn't thread into the body. I found the OE carb in a box of spare parts (never a good sign) and rebuilt it. Fresh gas, couple new fuel lines, proper vacuum line routing and it runs semi decent. No death rattles or mosquito killing smoke coming from it. But I did check the compression and it's at 126psi. Really low from spec. I've checked the valve clearance and set them. My question is should I keep going or scrap this project? Parts availability or being relatively affordable is not real good from what I'm seeing. Is there a good aftermarket supplier for this old model? Are newer models compatible with some parts? I'm of the belief that if I'm going to tear this thing apart and rebuild it then I'm going to go ahead and replace everything that is accessible while it's apart. I just don't want a ton of moola wrapped up in it. Any help, advice or criticism is appreciated!!