I attached a spreadsheet to the OP of my no sparge brewing
thread. It assumes 95% conversion efficiency, and is dead on with my brews so far. The key is to adjust mash pH, whereas I would typically use salts in the mash and phosphoric acid in the sparge water I add them both up front.
Efficiency drops about 2% for every pound of grain you add to the grainbill, so I don't consider no-sparge practical over 1.060 unless you are planning to partigyle.