For the record if youre gonna part out one of those cars theyre the W-Body designation. G-bodies were the old style of Grand Prix's and Monte's. Once they switched to FWD their designation is changed to W. That should help you at least grab a few search results and curious lookers
As for whats value there are a lot of cars that came with the L67's so motor wise you wont get much love. Transmissions will probably net you more than the motor but still nothing spectacular (read nothing hugely over 100 bucks). Honestly though outside the usual headlights/tails and perfect side skirts that hold good value on every car. I would be some money that an early HUD for the GTP's would fetch a few good dollars but I wouldnt pay anything over a few hundred bucks for a scrapper...that is unless you can use any parts. best effort is to rip everything good off and send the body to the crusher for a few extra bucks