I'm sorry Rob. I thought all Homies used the smaller sparkplugs like we have here in the U.S.
You could temporarily use the old boot-cap from the old magneto to get it running for sure. I do have the larger 3/4" hex caps here. You can also use a Bosch shielded cap if you can find them there in The Netherlands.
Things are so different in your country, I keep forgetting how easy it is here to get the correct parts you need.

John