Super six intake manifold assembly

Hi there, I'm new here, and am restoring a 68 Dart. She only has 40K "ORIGINAL MILES!" I just replaced the heater core, thermostat, & housing, all the hoses etc... I broke one of the cables off of the heater box, and need a new one. Does anybody know where I can find such a piece?

Also, I would like a different manifold to increase HP. I have an HP440 on an engine stand, but not sure I want to change it since it is all original. :/ I would like a 4bbl manifold, if anybody has one, please PM me.

Thanks!