To be honest there isn't much between an AMD and Intel Hack. There used to be a huge difference but with the development of OpenCore that differentiation has shrunk.
You will get a new AMD CPU with 8+ cores and 16+ Threads for a lot less money than an equivalent Intel CPU. You need to use the iMac Pro SMBIOS with AMD CPU's, as even if they have a built-in GPU. As AMD APU's won't ever work in macOS.
If budget is the driving factor for your current build then looking at an AMD Rig would be sensible. You would still be able to use your R9 280 dGPU. Memory would be DDR4 and you can add a compatible WiFi/BT card easily for around £50 or less.
They can still cost a fair bit, I built a decently specified system, to Dual Boot Windows 10 & Catalina, for my nephew for Christmas. It cost my sister around £1,100, as it was a completely new build with no previous rigs to pull things out of to save money. Obviously you can build them cheaper, but he wanted Windows Gaming as one of the main uses, so a decent spec was required.
There is a bit of a steep learning curve when opting for an AMD hack. Simply because you have to use OpenCore and it can take a little getting used to before you get everything up and running. There are some really good guides over at the Dortania site -
https://dortania.github.io/OpenCore-Install-Guide/. With guides for AMD and Intel systems.