Welcome to the forum Tom,
I'm in the UK, so I have experience of the high US to Europe shipping costs you refer to - inevitably inflated by additional import duties/taxes, making such purchases uneconomical. Don't worry though, the easiest way to solve your issue is to simply purchase a stock motor - which will be 66cc despite being labelled 80cc - from the hundreds listed on European eBay. Then add your preferred upgrades by purchasing any parts such as aftermarket carb, CDI, exhaust, cnc'd high compression head etc. from the gazillion Chinese eBay, AliBaba or AliExpress sellers who mass produce/market the parts in the first place and invariably list them with free worldwide shipping or charge a measly price for postage. I do this all the time without ever encountering any problems or having to pay any import duties/taxes, so I speak from experience. Goods are well packed and in most cases shipping times from China are often never more than 7-10 days - sometimes less. Buy with confidence - then share pics of your build here.