makes me wish there was a Free Geek in my state. I did find a 637CD Money Magazine at an ewaste facility a few towns away from me. Anyone willing to donate a full 68040?
Which logic board are you using? There are certain ones that require the addition of a 3.3V regulator and additional power supply per https://powercc.org/psu/
for 32-bit 68K Macs, they'll probably survive up to 2040, and I bet you future patches will make them work. For PowerPC, I imagine they can process years well after 2040, especially G3 and newer