The HO engine is higher compression and therefore has a "risk" of pinging on lower grade fuels. Therefore the HO ECU uses knock sensors to listen for pinging and will then adjust the timing to prevent it.
HOWEVER, I have never noted any pinging on a HO with any fuels in the UK - and I don't have my knock sensor fitted to my engine. So, the risks are low if you use proper fuels (in my opinion). But listen for it and you'll know.
However, the non-HO ECU and non-HO wiring harness has NO provision for knock sensors, so this is not an option.
Your only option is to test fuels and listen for pinging and base your fueling decisions on that.
No other changes are needed (i.e. fuel pumps etc).