Which bootloader and macos version would be best for a q6600/9400 and asus p5b (old socket 775)?

Currently have mojave on my 4690k but that's way too good a system for what I want to do. I do have a q9400 in a dell inspiron 545, but proprietary motherboards almost never work on a hackintosh, do they? I also have a boatload of older amd and nvidia video cards that would work with older versions.