Installing headers -- While engine pulled or after re-installed?
Why are you going TTI? I've read more horror stories about people beatin the SNOT out of them to make them fit than any other brand, hands down. I put Dougs on my 65 Valiant with an LA 360 and while it was a bit of work, they were the best fitting headers I have ever installed in my life. So I can only imagine how much more room you have in a later A body. Aren't the exhaust flanges from LA to Magnum the same? If so, It'd be Dougs for me all the way.