This is a super-close match: https://stason.org/TULARC/pc/motherboards/A/A … -MAIN-BOAR.html though it declares the chipset as UNI rather than SIS. Probably just need to browse the other line drawings until you find another one that matches.

Looks like I was mistaken about the cpu:

Also here is a post screen I got from the person who sent it to me before I got the pc if it helps finding out what the motherboard is: