Hello dan-o

Why do you want to use a std plug??? You will get better fuel mileage, better performances, more RPM etc with a turbo plug!!!
You should maybe try RB N°5 plugs to open the tuning window if it's too hard to get the proper tuning, but I don't recommend to go back to a std button head!
If not, you can just change the combustion chamber to a std one.