Doug’s or tti headers

I've used TTi's on a 70 Dart and a 75 Dart Sport, both 360/727 cars, with power steering, with no problems in either installation. There are plenty of members that have had similar experiences with Doug's. They aren't cheap, but worth the $$ IMO.
I took a set of cheapo headers off of the 75, probably similar to the ones you have, wall hangers now.