Is the cruise control vacuum line an acceptable vacuum source for a supercharger boost gauge/FMU/and Ignition Boost Controller or do I need to tee in to the vacuum line right at the intake manifold?

I wouldn't use it for a couple of reasons, the primary one being the check valve that doesn't allow vacuum to drop off when you open the throttle. GM puts a check valve in that line (along with a vacuum reservoir) so that your curise control and HVAC controls still have vacuum to operate them briefly if you happen to smack the throttle open to pass somebody, climb a steep hill, etc.

I'd do a fresh line straight off the intake for a vacuum connection that important.

Thanks Damon.

I was concerned about that fat little valve and possible affects of the cruise control servo operation on the SC equipement that requires a vacuum source but tried it since that hose goes right by the FMU, boost gauge MAP sensor and MSD box.

I'll go straight to the intake manifold upstream from the check valve.

Just tee into the fuel pressure regulator port on the back of the plenum....