Looking for some Differential advice

some better gears would certainly help your slant, but you might want to say what you are going to do with the car. 3.73s are pretty low if you get out on the highway at all. You'll find yourself running out of 3rd gear and winding up that slant at 70 mph. I'd pick 3.23s for a run around drive it anywhere car.
Save it money, go to a rpm/tire size, final drive ratio calculator, cut rpm down with taller tires