I think that you're asking for trouble.
Orks can pretty much do anything better than any other army. You can specialize and be phenomenal at it. However, you can't really make a well-rounded Ork army and pretend to be green space marines.
I'm not sure what you're trying to do here? Be an assault army? Be a shooting army? That's a lot of Battlewagons tying up points not doing a whole lot.
When I use Battlewagons, its for one of two purposes:
1. They're full of Lootas, they sit on my back table edge and unload on everything. They have a 48" range, and the board is only 48" across. Meanwhile, my Battlewagons are chock full of rokkits and maybe a Zzap Gun or a Kannon to shoot at anything that draws near.
2. they're full of Boyz, or in my case 'Ard Boyz, oftentimes with Mad Dok attached to them; a 10 point model with a 4+ armor and
FNP is nasty; and when they're cruising up the table in an armored battlewagon, they're even nastier. That battlewagon needs red paint, a Deffrolla, and a single big shoota to avoid getting immobilized if you get hit for a weapon destroyed result. It'll be moving 13" every turn, so won't be doing any shooting.
As it is, I'm not sure what you're trying to do. If your Orks come up against my Orks, I'm going to eat your army 1/2 at a time. I either play 100% assault, or 100% shooting. I pretty much kill everyone with a bit of tactical work, but that's because I use Orks thematically.
If you want a shooty list, take a couple of shokk attack guns, stick them in a couple of battlewagons with Lootas, put a bunch of Shoota Boyz on the ground, give them a 29 man gretchin squad to make them all 4+ cover saves, and add in a few Killa Kans...Rokkit Buggies....Deff Koptas...whatever your fancy is for a mobile reactionary force. Shoota boyz with a nob+
PK, and you've got a LOT of shots and a heck of a good assault unit.
Alternatively, if you want an assault army, either mechanize them in trukks, or make gigantic foot slogging lists. Personally, I like having 4 trukks clustered around a battlewagon, with 'Ard Boyz and a Mek +
KFF in the battlewagon giving cover saves to my trukks as they roll across the field to assault something. With Ghazghkull in my list, I have a 27" assault range. No one is ever ready for that.