How much rwhp you makeing with that vortech? I put down about 390 to 400rwhp the last time i hit less then 150, i can tell you that the car was outta steam, it wasnt a governor.
In my experience you feel a governor. its not like the car just gets to 120 and stays there. In the cars i have felt its either cutting the rpms, which you feel, or its cutting the fuel which you feel. the car will studder, drop speed and rpms, pick them back up and then drop them again.
If its just hanging there, then sorry she is just done.
I dont know what the stop speed of a charger is, i know the last time i was at 145+, it was against a charger srt8 modded, 5 times from a 80 roll, i gave him a car to start, walked around him each time and was a car ahead at like 145. but at those speeds im not looking down. and any bend in the road my stang didnt feel to stable up there that night, and i have a lot of suspension mods.