There is no "Bare metal programming for macs" book. The information you have is more or less the best publicly available information. Guide to the Macintosh Family Hardware is essentially the SE/30 (and family) version of the 650's developer notes you linked to. Designing Cards and Drivers will help if you want to make an expansion board, write a declaration ROM or similar, but it's not really of that much use when wanting to talk directly to the SE/30 hardware.

You can look at the NetBSD and Linux sources, since both run on the machines you're interested in. You can also look at the MESS sources as an SE/30 reference. That and spend hours and hours staring at disassembled ROM and/or System code.