Hi fellas, I am working with a 7J series D4. The engine hunts at idle.  Pretty big rpm swing, maybe 100 to 150 rpm. Fuel gauge pegs when running. I do have a couple injectors leaking around the base when running and looks like the fuel return or overflow line coming from top of injectors has been purposely pinched off. Haven't opened anything yet to look but wondering what in fact I could check that will cause this issue.  I've included a pic of the area just to help verify what I'm working with. 
thanks in advance guys. 

Hi DC,
first thing I would rectify is allowing the injector leak past drain lines to drain as designed--if pressure builds up in the upper section of the injector I could see the issue you mention occurring. The injector drain lines were manifolded together and drained onto the ground--not an issue back in the day but not so now.
All these old injectors leak fuel past the internal needle and body and must drain freely--on later units a bypass drain line was fitted to drain back to the fuel transfer pump inlet via a port in the pump body that early T/pumps did not have so you would need to tee into the pressure bypass valve housing as shown as a representative example below--your situation may vary as needed.
Cheers,
Eddie B.