The core of my army is allmost like the orklist you posted. a truck and bike-army is fun to play! The only thing i think is that wazdakka is quit expensive for a 500pts list, mayby exchange him for a cheap warboss or big mek and take an extra trukk with a pile of boyz in it?
If you want to go for a bigger list, it's maybe worth thinking of taking warboss on bike and nobbikers as troop, instead of wazdakka and regular warbikers.
IMO, this combo is just better