Recently had similar issue with my daughters H6 subaru and it was caused by air con condensor blocked in lower half, the condensor was changed and overheating at lights and in bumper to bumper traffic ceased. Just a thought.
I have done three of these and never bothered with grub screwing. Get it all welded before decking and I use a genuine RB26dett head gasket. See the picture.
According to QLD TMR Minor Modifications Document ;
Headlights
Retro-fitting of gas discharge headlamps (commonly known as HID headlamps) and Light Emitting Diode (LED) headlamps to vehicles that were not originally supplied with such headlamps is only permissible if it can be shown that the:
• headlamp self-levelling device is fitted
• headlamp wiper and washer system is fitted
• complete headlamp assemblies, and not just the HID or LED globes, are certified to ADR or UN ECE Regs (with appropriate markings).
Just means that both size PCD could be produced from one wheel mould its actually efficient manufacture and cost effective. The holes for wheel mounting have simply been drilled last rather than cast.
You are confusing The Wheel Manufacturer, with a company that gives a f**k.
Have you fitted a new fuel pump relay, had similar problems with one of mine, would drop out, but work again after a short pause. See the thread on this site R33 Fuel pump Relay Issues, has plenty of helpful advice.