I don't like that battlewagon... You will arch forward and opponent will kill BW and burnas and then go after boyz... Either spam the wagons or don't take them...
Same thing with stormboyz... You'll find yourself split and attacking opponent in waves... Stormboyz die as easy as normal boyz... And you will have them in front with battlewagon which means they will get shoot...
There are 3 solutions that come in my mind:
First is to drop out bw, burnas and stormboyz and add 6 kanz with rokkits... Then add more boyz and with rest of the pts you can add lootas or buzzsaw koptas...
Second is same, except that you add tonz of boyz, lootas and buzzsaw koptas, without kanz... That will allow you to play horde which is still very effective at this pts... I'd go with this list (put in buzzsaw, 2x5 lootas and 80 boyz with warphead or warboss) or with mini kanz wall list...
Third solution is to ply 2 battlewagons with boyz, stormboyz who advance behind them, buzzsaw kopta, lootas and few gretchins to babysit home objectives... I wouldn't recommend playing mech list bellow 1250pts, as 2 BW can't pose enough threat...
As you see, each solutions makes your opponent to deal with entire army at once... And this is how the orks have to be played... Every army that you play against will try to single out your units and take them one at the time... In order to win, you must not let him outplay you...
In any case, orks are kind of army that has to specialize... And not to allow opponent to pick one part of the army at the time...
Hope this helps