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Your best bet on new foam is a junk yard. Go find a wrecked F150 with low miles and grab the passenger seat (assuming you have the 40/20/40 seats. If you have a bench, it's tougher obviously.
As for the height - you'll be amazed how much higher you sit on new foam -and wires under the foam as you'll probably find a few broken when you change out the foam. So, if say hold off on shimming the seat till you rebuild it...
If you do need it, just stacking some thick washers is the only kit you need :-)
There are some decent seat rebuild threads on this forum. I have one from a while ago I can post when on a computer....