From your description, what I can say is you're not getting appropriate weight transfer, and the tires are unloading shortly after you launch (but you already know this). Here are some thoughts I'll throw out - if nothing else, it will provoke someone else to jump in and correct me if I stray off course ;-)
1) First and foremost, what settings are you using on the shocks and struts? This information will help. The shocks should be mid-range to start. Set the struts full loose.
2) How much front end travel do you have? In other words, how many inches can you jack the front end up before the tires lift from the ground (measured to the center of the wheel well). My guess is that your car might be sitting too low in front. If I remember correctly, you need about 5" of travel - if you have more than that, you can raise the front which should help in the weight transfer department.
3) I would argue that you may want to use a lighter spring up front - perhaps 135# or even 125#. But this will depend on how much front end travel you have right now (I think). The last thing you want is coil bind when the car sits back down on launch
4) Do you know what the pinion angle is set at? The optimal setting will depend on the composition of the control arm bearings (solid versus synthetic).
Finally, does your car squat bad on the launch? This may also contribute to the unloading you are experiencing. I hope this helps some.
BTW - if you haven't read Kevin Slaby's "how to launch a drag car" over on the
www.baselinesuspensions.com web site, then do that now.