SSS,
You bring up a good point and I should have clarified my post. Back in 1972 I built a boat motor with a 6-71 GMC supercharger but it had no teflon strips in it, and it ran fine with out the blower belt hooked up, and that is how I broke my cam in on that motor. A screw blower should work also as there is no friction on the case the way they are made.
I don't have any experience with a GMC blower set up with teflon, so they may not turn as free because of the friction of the teflon against the case, so someone else will have to chime in on that type of set up.
I guess you could say the rule of thumb would be if you can spin the blower with you hand, the motor should run without the blower belt. This would be for a blower mounted on top of the motor. Others types that have 10 feet of intake tract might not work.
Tom G.