VBB2T 8" to 10" conversion (Sip Steering column)

Hi, thanks for your attention.
I would like to upgrade my vbb2t with a Sip 70011500 conversion steering column and a drum brake (from a T5), I think that the disc is too much eye-catcher for an old vespa.

These are the questions:
- which kind of shock absorber I have to buy? All pk's or only a shortened one?
- which kind of shock absorber base plate? The pk's original or the one with a 4mm offset?
- If I put a 10" gs rim on the rear, will I have troubles of wheel alignement?