Thanks guys. I looked again and then I was "inspired" to look at the FSM to see what it said. (well, duh, dummy!
) You guys are right, all it wants is a vacuum source.
It wasn't set up correctly when I bought it. In fact the fuel return line had somehow disappeared as well. Since I'm rebuilding and considering a future move to FI I want to restore the return line. The Evap was there but the original air cleaner was gone and the purge hose wasn't hooked up to anything.
The book says originally the purge hose was just hooked into the air cleaner horn; it doesn't require that much of a vacuum at all. I think you're right in that although the power brake port would establish the vacuum, the airflow might be too large and cause problems.
Thanks for the sounding board.