Quoted from nigel:What I'm curious about is the value or use of the old boards. Is this useful to anyone?
$20-$30 on the driver board. The MPU and power supply don't really have much value in an untested or non-working state. The interconnect harness might be $10-$20.
Quoted from nigel:Like if I turn it into an art project will the pinball world be out to get me?
Yes, you will need to flee like Frankenstein's monster. I'm kidding. Maybe.
Generally speaking, the ideal approach is to repair a game to working condition, and most people prefer that any modifications that aren't stock to be easily reversible with no lasting damage. Chances are that you probably won't keep the game forever, and irreversible customizations would make the game incredibly difficult to sell when that time comes.
Aftermarket parts are perfectly fine. Replacement boards, especially for system 1 games that had a terrible boardset design to begin with, are fine as well.
Quoted from nigel:Just want to make sure I don't mess up something useful or rare or whatever because of my own ignorance.
Feel free to ask all the questions you need, and folks will likely point you in the right direction.
For system 1 game repair, there are two main central repositories of knowledge:
http://pinrepair.com/sys1/
https://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_1