I used the ECE kit years ago. I did a 4 inch drop so I got the adjustable panhard bar, not the trackbar that attaches to the TA.
My memory is kind of fuzzy but I THINK that the panhard bar might attach to a different location with the shock relocator kit.
I would talk to them again about the panhard bar because I might be wrong. The track bar is only meant for drops of more than 4".
But if you're looking to get a 5 bolt lug out of an anything other than a 71-72 AND run stock height AND use coil springs, you would have to find some way attach the panhard bar.
Ok, now after writing all that out I see your problem. I've also heard others mention an axle swap or redrilling the axles for 5 lugs.