Welcome sir, and great looking ride!
The 76' and 77' models have a few things different than other years, namely power steering and brakes, and a different steering geometry system than previous years. Yours has a lot of trick stuff that someone added to their taste, the rear disc brakes are neat.
I'm surprised it drives well, or maybe it doesn't? Obviously rough with the dual shocks and seriously massive rear leaf!
How does it respond when you hit a dip in the road, pothole, or go over a ridge at 45+mph and unload the suspension? As dirtdonk mentioned there are some steering geometry parts that historically don't work well together.
For some reason that I can't explain, back in the day many times flares were installed not-even-close to "center". And I realize "center" means different things to different people; center of the sheet metal, center between the gas filler caps, center between the inner fender sheet metal, or?
On yours obviously the clearance between the front gas filler cap and rear cap is different. There is a sheet metal brace, that is really just a smallish 5/16" steel rod, holding that piece of forward sheet metal that often times people are reluctant to cut. Therefore the outer sheet metal gets cut and the flare installed too far back. Then to make things worse is the shape of the flare. Notice the sharp radius of the forward slope on the rear flare, compared to the gentle radius on the rear part of the rear flare. So when viewed from the side the front part of the rear tire is much closer to the flare than the rear part of the tire.
In short there is not easy fix, although there are some things you can to make it better. WH sells some flares that are *really* flexible and almost stretchy. With great care you could trim a little more forward on the sheet metal and then install these new style flares. However they only come in black and would need painted to match you're already color-matched flares.
Another option is to move the rear diff housing back a little. This takes a little work, but not a tough job. You'll need to remove the rear housing, cut the existing leaf spring perches off, then weld new ones back on with an offset hole for the leaf spring center pin.
That said, if it were mine and my intended use was to drive it on the street because its a cool old classic I wouldn't install new flares or move the housing back. Just fix the front end parts, remove some shocks so you end up with 1 on each corner. And if you want a smoother ride change out the rear leaf springs and lift block (throw that block in the trash can) for a new/soft style 11 leaf pack. Cheers!