Like a few other guys are saying, find a different charger. If that 64 has a 71 or 74 turbine, your going to have to run high RPMs to keep the charger spooled and happy. It's all about turbo sizing on VP trucks cause there isn't a lot of adjustability like the CRs. I've ran probably 12 different turbo setups on my vp truck. Best setup I ever ran was a 62/65-12/475 with an external gate. Super fast spooling setup that always ran cool. I ran 240hp Mach7 injectors, A Hot Edge Juice, and also had a Smarty I would run sometimes. Truck was a 6spd on 35's at the time and I pulled 10-20k often. I have had good luck with the HE351's and 150hp injectors lately for towing my drag truck on my gooseneck, total weig is just shy of 21k.