I finally got around to plugging this into brew target and I can see the mash may be problematic.
Targeting a 6.5 gal boil size, it will take most of the water for the mash, leaving very little to sparge. I'm speculating that is why the original recipe included DME. His equipment probably couldn't handle the required grain load. In all honesty, I'm not sure my mash tun will hold this much grain. Must be time for an upgrade!
I'm going to play with this some more. Maybe someone can verify what they are seeing for the mash.
This is not a problem, though. I can go to larger boil volume or drop in some DME like the original brewer. I'm going to ponder...