Quoted from zacaj:a -35 will not work. Stern MPU-200 has more RAM than a bally board. a MPU-200 can be down-converted to be used as a -35, but not the other way around.
Both barakandl (https://nvram.weebly.com/new-pcbs.html) and Alltek sell new boards that can be used in any MPU-100/200 and Bally -17/-35 games
The -35 can be converted to a -200 thanks to barakandl
https://nvram.weebly.com/repair--conversion-kits.html