Just throwin it out there, but for that amount of bushels, why not just put heat and air (I hate stirators, but maybe put em in too) in the bin?

Got a buddy down in Wood Lake that has two 35,000 bu bins with big HP fans and numerous vents..... No dryer, just air.    Its not perfect (no system is), but its working very well for him.......

Good luck

PS:  FSA is almost giving you money to build grain systems.