IMO
The rear spring rate will be a lot more critical than the front...
especially with drag racing. The same could almost be said
about valving....but the front and rear are both critical
for a proper launch. Just make sure your dampers (shocks) are properly set-up for drag racing..not street or roadracing.
I was getting ready to say that spring length won't matter squat
on a drag car...but then thought about it for a minute. If I'm wrong on this one...someone speak up. The front spring length
shouldn't be much of an issue...so use the 8 or 9 if you have a
short travel distance (save a little weight). Considering the
rear valving used...I would go for a little longer rear spring to prevent total compression of the spring during rear weight transfer. Then it all leads back to spring rate and compression
settings
Have fun and good luck.
Jeff