I have a little experience in earth moving, just enough to be dangerous, but when you are talking about moving dirt up to 600 ft, dozers will not be efficient at that, scrapers are pretty much the only way to go with that, way more efficient even then an excavator and a couple dump trucks, and then you still have to go out and spread the piles on the other end, and yes I said a couple dump trucks, if not you will have the excavator sitting idle while the truck is hauling and dumping, that costs money. a scraper will move almost the same amount of dirt, if not a good bit more, in one pass, and the dirt will be flat and spread out when it lands.
Will the covenants allow you to stockpile the topsoil temporarily, as in a yr, so that you can get it sold for a decent price? that would help.
Also, if I remember correctly, you said you had about 30 acres that you were spreading these spoils on, even if you have only a few inches of good topsoil, that is a huge amount of topsoil that you will be covering up with barren clay if you don't strip it first.
When you are talking about scrapers, Caterpillar will probably not be your best option either, most of them are pulled anymore with huge farm tractors, to the point of John Deere making some of their big 4wd tractors labeled as scraper specials. they are fully equipped, along with two pans, that are pretty much auto loading and dumping, might take a person a minute to figure out how to most efficiently run them to their full potential.
I built my 15 acre pond entirely with scrapers, at one point in the deeper cuts we wound up bringing in a D6 with a ripper to rip the hard pan so the scrapers could get a full load quicker, the ground got too hard for the smooth cutting edges of a scraper, it didn't have enough down pressure to fill the 24 yrd pan in a reasonably short distance.
Hope the information is helpful, let us know how it goes, Good Luck!
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