I run this " european engine"  with several ignitions, ranging from RCexcl to Vlach, to ICU, all set at 0.020 to 0.022" gap using CM6, Brisk UR17, and  NGK BMR6F plugs.
Hard starting never is a result of the use of these parts/settings, but always is in the fuel and/or carb settings, fouled plugs etcetera.
If the carb is set right, and the plug is brownish or light tan, starting is OK regardless of slightly wider plug gaps, even up to 0.027"
Like TOM said, if the engine is operated at 10,000 rpm or more, wider gaps may not get up to the required spark energy to bridge the gap, but below that rpm, I have not seen any problems at all.