Tuning help

I currently have a Procharged 600B Trans am with a small block chevy. The engine was built for a blower and when I first got the car last spring I dynoed it at 300 RWHP after chaning the fuel pump/regulator/carb/hat I am still having problems getting this running right. I brought it to the dyno a couple of weeks ago and only made 216 RWHP with an a/f @ 18 running 5500rpm 10lbs of boost with good steady fuel pressure. I'm running 68 main and 76 rear jets in my CSU carb. We're leaning to my torque converter being way to tight to let it actually make any low end power, but I am on the verge of giving up I don't know whats wrong with it. Any suggestions?