Need advice upgrading old Hackintosh to 4K

I have a rather old Hackintosh built on a Gigabyte GA-X58A-UD3R mobo.

When I got it, it took several months of tinkering to get it to work with my videocard; I tried both Nvidia and Radeon; ended up sticking with Nvidia.

It's been in the closet for a couple of years, and now I'm trying to get it up and running again.

Everything still works, except

1. The video card is old and doesn't support my new 4K display
2. No audio output of any kind

Can someone recommend a video card that would support 4K 60fps over DisplayPort, which "should" work without too much tinkering around with drivers?

And is there any "easy" way to get Audio working?

I'm pretty sure my bootloader is still the "old" Chimera (or maybe Chameleon?) It's not the "new" one (Clover?) that allows for software updates etc. (Mainly because I tried to upgrade at one point but was told it was not possible with my old mobo.)

Thanks in advance for any advice!