Welcome a fellow Arizonan!
You might want to fill out your profile, I'm guessing on a lot of your drivetrain.
With an 81 you shouldn't have a t5 but I'm going to assume that's what transmission your running. It has a .86 overdrive and I'm guessing your 33's are actually measured about 32 (might want to take a tape measure to them to find out)
Here's a good calculator for cruising rpm I'm not sure what the 4cyl power band is but doing 65 mph with 4.56 your looking at 2676 rpm and with 4.88 your looking at 2864
Also going any higher than 3.73s you'll need a new carrier for your Dana 30