I put a summit kit on my Dart 340 with tti headers.
You have to fab some pieces. It works fine up until the very front pipe on each side. They require some cutting and welding.
Did you start at the rear and work forward? That's the best way to do it, IMHO.
The kit is designed for Hooker comp headers which have very different collector locations from some other brands.
What do you want for the summit kit. Shipping would be a killer.