I like your list a lot, and despite your claims of only being semi competitive I think it's a plenty competitive list.
The changes I'd make would mostly be structural ones. I'd split the warbikers into four units. One unit of five bikers with warboss and painboy, three
msu, one with zhad attached to scout or outflank. If he's outflanking he won't need as much protection so you can play zhad with no painboy, using him to buff your tank boss instead, with his tank buff. The problem to star lists like yours is they get tarpit tied by
Msu armies and lose on objectives. Most competitive lists run min sized squad with max special weapons, so we're talking 3-5 models. Two war bosses and a dozen bikers is just overkill, shooting or
cc. Which is the other thing, bikers are actually better at shooting than
cc, while the bosses are
cc all the way. Give them just enough bodies to survive and let the rest shoot up the enemy. E: if you do run into a situation where you need two warboss at once, coordinate simotaneous charges. Orks are all about lining up your charges like pool shots and then watching the balls sink. Koptas eat overwatch,
MANz missile assaults from a trukk to deal and take w's, zhad jumps in after arriving from outflank last turn so he can sweep the enemy after your
MANz break them.
You can apply this principal across the rest of the list. Do 4x1 koptas. If you dropped the bustas and lootas to min squad size, you could take another unit of one or the other.
It's still boyz before toys, but this edition the boyz in the metaphor are whole squads at minimum size. Organize your squads to max out the number you can take in your
foc and work from there.