HD4600 iGPU - can't work out how to enable 4k Resolution

Opencore 0.5.9 - Vanilla Guide Catalina 10.15.5 Haswell i7 4790K Gigabyte z97x Gaming-GT using onboard Intel HD 4600 LG 27 inch 4k monitor Either HDMI or DP - both with the same result 

Hi there

Using the default values as per the Vanilla desktop Opencore guide, I'm able to get graphics acceleration, but only at 2560 x 1440 - doesn't matter if I use DP or HDMI.

I'm wanting to run at 3840x2160 but cannot work out / understand how to enable this.

I can't make sense of the whatevergreen framebuffer faq (which is what i'm assuming is where this needs to be set)

If I change the AAPL,ig-platform-id from 0300220D I can get higher res, but the kext doesn't load and there's no graphics acceleration - terrible performance and slow boot time.

Can anyone point me in the right direction?

Thank you