I know it hasn't been brewed but my issue is that if the est. efficiency is that high then the actual efficiency will be way off, throwing bitterness, final gravity, and alcohol off.
It's saying the mash volume needed is 7.99 gallons when my actual mash tun is 10 gallons. What I do see that's different from the rest of my brews is that it requires a 3 step (instead of 2 step) batch sparge. That might be the issue. The dead space on my mash tun is right at .75 gallons but I add .5 a gallon because every all grain batch so far has come up about a half gallon short for whatever reason...seems like no matter how diligent I am on the numbers, my final volume is always low so I added that in there to make up for it.
I might try dropping the OG to see if it will change back down to a 2 step sparge. The small problem with that is that this is the beer I plan to drink with my first born on his/her 21st birthday while having 5 or 6 bottles in the years between. The SWMBO and I are trying to get pregnant now and I would like to get this as high of alcohol as I can so I can let it age long enough to hit that 20+ years with no major issues. It might be a tall order but I'm really trying to figure out how to make this work and not end up with a beer at half the gravity/numbers that I'm expecting.