Dougs D453 headers went in ti my 70 Dart yesterday....

You guys are making this a whole lot harder/longer than nec .
Having the engine in the right place helps .
Footnote #39
You have a huge engine fan blowing a lotta air to cool .
Search my name, I have gone thru install tips a few times.
Good luck .
2 electric fans here
Tubes still too close to box, will Install a. Heat insulating blanket