Header is rubbing frame - 70 Duster

Really hate to hear that......when I put my TTI's on my 340, they also fit like a glove (kinda like an OJ glove). I think that when sitting the engine into the compartment, I had to place a small shim under the engine mount bolt to raise it up about 1/4" to help in getting just a little more clearence on them. Don't know if this will help you or not with your current situation or not but it was a quick easy fix for me. Maybe it will help you.
Good Luck.
Greg..........mtn_jake