You can definitely get great power out of a side reed, not due to have the carb closer to the crank. It's mostly just due to the lack of limitation in carb sizing.
The treats side intake is about the cheapest you'll get. And I would still suggest running a full circle crank with that, which takes away some of that cheapness.
Declan's absolutely right, though. With Vespa, you either have to spend or build. The more you spend, the less finagling you'll have to do modifying components.
I have two set of bored stock cases, and while they are nice, the Malossi RV cases are perfect, and PERFECtly match the DEPS kit. It's nice to not have to worry about that stuff if you can afford it.
I will tell you, that even with the Pinasco and a good pipe, you'll always be limited by the 13.13, in terms of ultimate output. My pinasco setup is punchy as hell, but there's no way it's revving over 9k, ever. If you're looking to really get everything out of the cylinder, definitely future proof by having the option to increase your intake side flow.