I have worked on that same setup with lousy results. I should have replaced the ABS with a new unit but the only sure way I could get it to work was eliminated the unit all together to get my pedal back.
I had the 72 351CJ and wanted headers but couldn’t afford them at the time. I can’t remember but one side of the exhaust had a dog leg in the runner. I spent a little time grinding it out and it made a great difference. Never regretted it
Glad my son found this site for me. Now I know where my friends have been hanging.
Good Day everyone and
Mach 1000
Here to show my restomod of the 71-73 model or help anyone else out with there direction of build.