Hello, my name is XXXXX XXXXX I will try help you with this.
This engine was not intended to use unleaded fuel but it could be converted to do so.
However, there wasn't any way they were marked after modification to let you know.
I would advise you to use an additive in the fuel if you are uncertain.
It should also be run on 98 RON petrol.
You also need to retard the ignition timing a few degrees