The live axle is not as limiting as you might think if it is set up properly. For example, the air ride equipped Velocity Camaro recently did the autocross at the year one experience faster than an 08 Vette with the same driver. See:
http://www.ridetech.com/more/wp-cont...hp_article.pdf
It's running a Ford 9 no less-considerably more unsprung weigh than a 12 bolt.
I think you should go for it.
Good Luck!
Paul