I'm a huge believer in drag tires, especially if you're going to be spraying N2O. A torque converter is just going to make traction even more difficult. If you mount a good set of drag tires you'll not only launch harder, you should be able to spray out of the hole for even better times.

My 60's went from 2.4 to 1.66 by swapping from 28x10.5" drag radials to 28x13.5 E/T Streets (I also upgraded my headers, exhaust, and converter, but the tires were by far the biggest factor in the 60' improvement).