Living with 3.91's

Put 3.91’s in it and buy a real convertor. Those changes will really wake up a stock stroke smallblock.
With a 28 inch tire you should be able to run 60 on the highway comfortably under 3k I would think.
If you want to go fast, you have to give up something, especially stock stroke.
I drive my car around a good bit with 4.30’s and an 8 inch vert, but I don’t use the car for highway driving, just around town and country roads.
Another reason I don’t drive on the highway I have skinny’s on the front and drag radials on the car, same tires it runs 10.30’s at the track without swapping tires back and forth. Not good highway tires, imo.
Again, what do you want, it’s all about what makes you happy