Keihin pwk 28 or 33?

Schaltroller / Classic Motoscooters Vespa Largeframe
1

Is a 28 enough or should I go with the 33? Does a 33 fit without isue?

Motor: Worb5 workd Malossi 210 Kit; Worb5 longstroke crank (reed crank); MMW2 w/ standerd reeds, sip/jl pipe, and vespatronic