Rev to redline
 

Got header on my rebuilt 84 gsl, on startup it wants to rev to redline or worse, and I have to shut it down. Carb has been stripped and I think I capped all the vac lines except for the float vent. Dont think the throttle plates are open but I don't know for sure, scared to let it run don't want to blow up my new build, any ideas. New intake gaskets and carb rebuilt.

Sounds like a vacuum leak somewhere around the rebuilt carb.

All the way to redline sounds like the throttle cable is snagged on something.
Check your cable routing.
Take the air filter cover off and look down to see whether the throttle is open.

Would me removing the butterfly in the intake and not filling the holes be a leak the throttle plates are fully closed