I realized that it is a street car. But trying to run 11.50's & weighing 3800 LBS is asking a lot out of that Buick. It's not a BBC
Just suggesting something to help you run your numbers.
Having open dump 3" cutouts is going to change your A/F mixture by a lot. Not only that, most tracks have to be a certain DB level, if it is too loud, they will not let you run.
I thought B.O.P. like to run tall gears, they are torque monster engines. Not sure if the lower gears will help, you might spin too much, can't fit a big tire in there. Just thinking out loud. Don't mind me.
After you had the heads ported, what did they flow? What is the guys name that ported them?