which gear ratio for 1/8 drag strip?

If it was me, Id leave the 3.91s in there, for one good run and see what it traps at. Then get the exact right ratio by math.
Beats the heck outta doin it twice.
I'd also stick with the 2.45 low gear trans;Narrow powerband,narrow splits.Might be a touch slower on the 60', but will make it up down the road.