Gear ratio question

The rear end is for sure limited slip. Tire size was based on a chart from another site listing the factory measurements on BF Goodrich TA tires.
Trap speed was 102 mph.
I knew the gearing had seemed low from when I first bought the car, but I didn't give it a ton of thought until I had it at the track and barely had enough RPM'S to make it thru. 5500-5700 at traps, the motor will turn 6000 RPM but that's up there.
Perhaps as a double check in spring we'll take the cover off when we change differential fluid and count the two sets of teeth.

Anyhow, thanks for the input just wanted to make sure I was looking at the formula's correct. I'm new to the forum, new to actually owning an A body having wanted one for near 30 years and finally taking the plunge. Great forum, I'll enjoy getting my feet wet and posting more going forward.