I think my '80 Aspen has a 2.76 gear ratio, due to a little tag under the lowermost bolt on the rear, that says "2 7". Would y'all assume this is correct? Couple of questions. Can I install better gears in the existing rear? Is it possible to install sure-grip gears? Or is it best to install an entire rear axle? Never fooled with rear ends before, so I'm not too knowledgable about it. Thanks.

It would be best if you located a complete rearend assembly with a lower gear ratio and swap the complete axle assy.
You could swap the gears and install a new limited slip unit but to have all that work done by a shop would run $$$ ($600 to 800.00 is my guess)

Hey, say we wanted to do it ourselves, what would be involved? Do any modifications have to be made to the case to accept a suregrip unit, if one ever found one for a 7&1/4"? Can the crown & pinion be just swapped and the preload set, if it's a different ratio? Can it be done on the car without too much trouble? I know setting backlash is pretty finicky, but if I can do it on the car without the work of r+r'ing the axle I'd like to.

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

At this point, I'm mostly interested in installing better gears, at least 3:23 in my current 7 and a quarter one wheel peel. Sure grip can come later. I currently produce no where near enough power to tear it up anyway. I just can't stand merging onto the freeway and risk getting killed because a Yugo is faster. Hell, I could'nt spin the one wheel with this thing if it was on ice cubes! Can't beleive that Chrysler actually produced anything this slow.