Would be filling a 12 ring 48 foot bin so would be about 34.5 degrees on auger. Most corn would be under 15%, but might put 20k bushels of up to 18% corn in bottom of bin at start of harvest. Looking at a used Brandt 13110 hp+.  

Tractors that I have are 

Challenger MT 545B 126 pto hp

New Holland TM 175 161 pto hp

New Holland T7 235 188 pto hp

Also how well does this auger work for unloading both hopper on a 36' grain trailer without moving the semi? Which is what I have been doing with my Harvest 1384. Is there anything that I should watch out for on a used Brandt auger?