How to change gs150 vs5 rims to star rims?

i have one vespa gs150 vs5,

so i want to change gs150 vs5 rally rims to star rims( vs1~4)


then, i think i need vs1~4 ver brake drums and axles

but i cant find where can i buy them, sip ,ebay... etc etc any shops dont sell them!!

 is there no way?!? thanks!