soft loc or advanced launch question

[L79racer]

I/C is about 44" Tires were set at 12.5 lbs cold so, after the burnout they were problably at about 15 lbs. Shifting at 7200 got a little spin as apposed to the 4000 launch which spun a little before the engine pulled down. I think I was leaving at too low of a rpm. I'm thinking I should try a 6000 launch with the 28x11.5 slicks at 10 lbs and see what happens.