73 duster front brakes locking up when coming to a stop.

If you run your car without the front brakes working, but with the rear adjusters now working,
then
there is a good chance that after several hard stops, or backing up to finish the adjusting job, the self adjusters will tighten up the rear shoes excessively, and now you have a new problem. This is probably why the previous owner took that stuff outta there.

IDK why your fronts are not working correctly, there are several possibilities. But I'm still thinking it's the booster, which is really easy to check. and that control valve is really easy to break, if yur not careful during the set-up.