440 swap on slant six 73 duster

Why dont you tell us your experience and what worked for you?
Life got in the way.
My wife told me she was pregnant 2 weeks after the Schumscher Tri Y headers came.
Sold the whole project 2 weeks later. My research Indicated the tri y headers were a decent fit, Good for street/strip, producing lots If torque and great mid range, but left some horsepower on the table in the Upper range. A guy i corresponded with said that from 2500-5500 said that the headers made made a big difference and the engine pulled like a freight train in mid range.