Chaosy Orks

I'm not big on fluff having not read any of the novels and i was just wondering if there were any instances where the Orks were heavily allied with Chaos? I've got a TON of new Ork models and quite a few Chaos and was kind of looking to tie the two color schemes together somewhat.

You are allowed to do whatever you want with your models. sharing a paint scheme accross two different armies is doable. the two armies can be allied together, so you can play them together.

as long as things are within the rules and wysiwyg, nobody has any place to complain.

I get that, I was just looking for some background fluff/scenarios where this might have happened in the 40k universe to base it off of.

there's several instances where chaos has manipulated the orks into fighting for them.  they even use this in the original Dawn of War campaign storyline.