Radeon just hates being blacklisted. I finally got amdgpu to run, by blacklisting with a grub cmd command. Archwiki is extremely handy.
in /etc/default/grub i added GRUB_CMDLINE_LINUX="modprobe.blacklist=radeon"
then ran sudo update-grub
and waza, now lspci -k shows 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Hawaii PRO [Radeon R9 290/390] (rev 80)
Subsystem: Gigabyte Technology Co., Ltd Hawaii PRO [Radeon R9 290/390]
Kernel driver in use: amdgpu
Kernel modules: radeon, amdgpu"
The shrill of victory was sweet.
(And I know most of you probably know how to blacklist with a grub command, and how to update grub's configuration. I added that full description because I have a feeling that somebody will find this with a search engine, and my experience will be helpful to them.)