Thats one of the great things about orks, you can do pretty much whatever you want with them. The only limitation on this project though is that you would probably have to pack together quite a few guns/barrels to make sure they were a lot different to std shooters.
But saying that if you haven't already got any burnas, all you'd need is extra bodies & heads (even the
AOBR ones) and the burnas/lootas box set does give you enough bits to make both squads.
Then you could use your other bits to make a load of Flash Gitz!