Polini 177 kit

Hi Newbie on this forum, help needed please.

I have a 2011 LML star dlx 125 which I would like to upgrade possibly to a 166 or 177.

Polini kits seem quite good value and not too childishly noisy, plus they seem to be easier to install.

If I were to go for the polini 177 kit which crank would I need to upgrade with? ( do I need to get the correct length?)

My list began like this

Sito plus exhaust (already have this)

polini 177 kit jets included

24/24 carb (already have one)

racing crank ( no idea which) do I need spacers?

all new seals bearings etc

new plug

A friend will rebuild and tune it all but he is a bike mechanic and not familiar with vespa.

My mind is now blank any help appreciated :)