69Firebird400, welcome to the group! I have posted some good on line sources for just this info in a post at the bottom of this first page (or depending on when you check this, the top of page 2) titled "1968 350 Engine"

There you'll find a couple links to Steve's web pages with the scematics from the manuals scanned in, and one other with info on the Thermal Vacuum Switch, and the hose routing etc... Go take a look, and save the links for refernce.

Good luck, hope you get her figured out soon!

Brett - 67 Drop Top 455!