Not to rain on your parade but currently I see this system going for $400 on ebay or $130 for the board and am curious...what is compelling for you and this? I did not know when I first started coreboot but you can buy faster and newer open source firmware boards for less money - stuff that you can do real work on.
I would definitely get a KCMA-D8 or KGPE-D16[1] if you want something newer with open source firmware that works straight away but that's me. If you are a programmer and want to tinker/port coreboot there are other similar boards of the same class and era that would be a better fit too such as the TYAN systems.
[1]The D8/D16 are fast enough to compile modern software and can play modern games in a VM (via IOMMU-GFX) so you can use it for more than just tinkering - they also support the facebook version of OpenBMC (AFAIK there are two OpenBMC's versions the facebook and the IBM the second has more features and comes on the TALOS system but both are secure owner controlled remote access) via replacing the crappy vendor firmware on the ASMB4/5 module (D16 comes with module D8 doesn't) Both have working coreboot with no fiddling just compile and go same features as the factory BIOS...and the D8 can be had used for less than your U40.
I would also check out the TALOS 2; POWER is the future of high performance freedom computing as there will probably never be another owner controlled x86 system due to ME/PSP etc. It has open source firmware out of the box (not coreboot) but again you should start with a D8 or D16 and a decent compatible CPU.