I was recently dicking about with a PX that had some carb / oil leaks issues.
The best gasket of the few tried was a genuine Piaggio one from Ron Daley
stick it down with gasket sealer, chuck drive shaft in the bin, buy a jug to measure oil, take three hours to explain to a fuckwit owner how to mix oil in petrol tank, wait for FWO to bring it back siezed up, repeat ad infinitum /ad nauseum.