Greetings:
You'll have to decide for yourself, but what I did was add 60:1 premix to the tank and retained the pump. I have since concluded that the ratio needs to be closer to 75:1, but more oil is certainly safer than less, especially for break-in. THe pump supplies adequate oil for a 50cc demand. When the engine starts inhaling 65cc per stroke, you must find a way to supply at least a bit more oil. See the Dr. Spock thread.
I felt my Malossi build was stronger than the Contessa Polini, but the Malossi had extensive case porting I did. It also had an O-ringed cylinder head thanks to Scooterwerx's great skills. It actually began without a base gasket - just lapped the cylinder to the case and used Permatex copper. However that combined with the gasketless head was too much compression for a daily rider. It's the only time the starter struggled to turn it over - about 175 PSI measured cold. I reinstalled the base gasket later on; that's one nice thing about an o-ringed head - permits disassembly without having to chase down a head gasket every time.
The Polini looked like high quality, and it was an easy bolt-on job. I could have matched the case ports on it too, but it was my first assembly and, well... I knew even less than I know now. Both survived my tuning "skills" very well
. I think you'll be happy with either one. BTW I have a leftover 47mm gasket for either bore kit if you need.
