Ok, I THINK i may have got it working!!!
For posterity here are the amdgpu (amd proprietary) packages I had to install. I'm still running the open source drivers for video.
# rpm -qa | grep amdgpu libdrm-amdgpu-2.4.99-967956.el8.x86_64 libdrm-amdgpu-common-1.0.0-967956.el8.noarch clinfo-amdgpu-pro-19.50-967956.el8.x86_64 opencl-amdgpu-pro-comgr-19.50-967956.el8.x86_64 amdgpu-pro-core-19.50-967956.el8.noarch opencl-orca-amdgpu-pro-icd-19.50-967956.el8.x86_64 libopencl-amdgpu-pro-19.50-967956.el8.x86_64
There were two more things I had to do to get it working.
1. It seems most programs aren't smart enough to go through all the vendors in /etc/OpenCL/vendors and find the working one, they try the first and give up.
2. Once you have FAH running and it doesn't find a GPU the first time it stops looking and you can't add it manually. You have to edit /etc/fahclient/config.xml and remove the "GPU=False" line and restart FAHClient.
Thanks, Richard