How fast will it go?

We have been running A 75 stock 225/6 with over 100,000 miles, full body 72 TwIsTeR 3,170 pounds. The first pass 20.2 after A few mods, PowerPipe-DC Exhaust Manifolds, 2BBL carb, Pertronics dist kit, curv kit, 3200 10" converter, 3.91 now 8 3/4 we are running 27" tall tire, The stock cam pulls close to 4000rpm give or take A little. This is what we go through the traps @ peeerrrrfict!! Now running 17.78) How much faster will it go? We will put the turbo motor in when the E.T. stops droping with this stock motor!!! Still gettin the feel of the car, more seat time would be good anyway. Talk to yall soon. Hope this helps you slant/6 Don