I'm more awake now, for better or worse.
When you say UK ISO layout what exactly doesn't work? It seems very strange that the default firmware doesn't support it because you can add it alongside ANSI as the position of the switches show whether you want # next to ISO enter or / above ANSI, and the pads for the extra key next to shift are just hidden. If it's just that @ is on shift+2 you need to tell whatever it's connected to that it's a UK keyboard as the conversion from keycodes to characters isn't done on the board.
If the PCB works and is nearly the same as the DZ60 I can make a hex that will 'type' the pin names for the two extra columns then you can do whatever you want mapping wise though it's worth searching for firmware now you have the board name.
If the PCB works and the soldering looks good it's not worth the hassle of returning it and will be quicker to just get the firmware working.
Edit: Had a look at the DZ60 and the pinout is practically the same as the GH60. Then realised you haven't said which columns don't work using the DZ60 firmware so I don't know which do to exclude them...