I've got some experience with all the stores mentioned so far. As Toni (great store for Speed passion and other stuff) seems to focus on touring and pan cars when it comes to Yokomo, I ordered most of my parts at Asia Racing Team - thumbs up so far! I don't need to comment on eSeller as it seems... rcrace-and-drift is also a very good store, but I prefer a Europe-based source for bigger orders.
ART have the
conversion kit in stock; i'd give it a try.