A total revamp maybe worth the effort and expense...

But, it you can't stomach that, I would definitely work on removing those bullhead. You most likely have yellow bullheads. Brown and yellow bullhead are native to NJ the one in your pic appears to have white chin barbels which is the easiest way to tell the two apart, as brown bullheads have darker colored chin barbels.

The issue you face is that even if you do stocked adult LMB, the high turbidity in your pond will reduce their ability to prey on the stunted sunfish and bullheads. Plus, if there aren't any LMB in there currently it leads me to believe there is a water quality issue which maybe why a complete revamp maybe in your best interest. If you have a local lake nearby with some 10"-14" LMB, try catching a dozen or so and transplanting them back to your pond. You won't be out any money if they go belly up.

I would go the revamp route though...