Gearing and shifting 4 speed at the track

Uh, with those big old tall 28" tires out back even 4.10's aren't bad at all. I mean at 3,500 rpm you're doing 72 mph. That's only a couple mph lower than what I was doing with 3.55's and 26" tall tires and I'm daily driving on a freeway.

You can run 4.30's, pull 67 mph @ 3,500 in 4th and still hit 120 mph @ 6,200.

Here's a decent calculator, it even has an 833 option with pretty close gearing to what you've got.
Gear Ratio Calculator

As far as whether or not to shift into 4th, we'd have to know what speed you're trapping at. If it's much above 90 you're gonna have to hit 4th if you go 4.10's or better.