Stock suspension drag racers step in please.

I have a 69 dart that I use as a street/strip car.Trying to keep it as close to stock looking as possible.Well finally got my 416 in and running.Went to track hoping the prepped track would help.No such luck it just blows the 225/60-15 M/t drag radials off.The car has 4.88 gears which worked well with my hot 340 but not here.90-10 shocks up front.Heavy duty rear springs.Springs have the off set kit installed.4200 converter.Left in 2nd gear 1 pass and went 7.30 with a 1.58 60 ft. That's thru mufflers in full street trim.Frame is tied.I could go to 275/60 or slicks.But really what I am asking is your opinion on what needs to be done to get car to hook up without butchering it up.Thanks Kevin.