Help getting started with an HP Prodesk 800 G1 and Monterey

Brand new to Hackintosh and I have an HP Prodesk 800 G1 system (Haswell i5-4570 with Intel HD 4600 iGPU).

I've managed to get Monterey installed and working fine when using a single monitor (connected via one of onboard/iGPU DisplayPort). I'd like to also be able to connect a second monitor (to the other onboard Display Port) - but as soon as I do, I get at the EFI splashscreen:

OCC: Failed to set mode 2 (prev 1) with 1920x1200 resolution Halting on critical error 

When connecting a dual monitor

I'm using a prebuilt EFI that I've downloaded from here:

https://www.insanelymac.com/forum/topic/323180-ventura-monterey-big-sur-catalina-mojave-high-sierra-on-hp-800-g1-usdtsff-and-tower-pcs/

A direct link to the EFI that I'm using is at:

https://drive.google.com/uc?export=download&id=1Y-DxJdZjbPmniS7ak68REdYmboAvPaqd

I was hoping someone might be able to step me through what I need to do to modify the existing EFI to get my setup working with dual monitors ?

I started reading up on Hackintool, but got pretty lost - I might need someone to help walk me through things if that's at all possible.

Thanks in Advance