A Ford 101, 3 bottom, 14" plow doesn't slow down a M7040 at all - even in ground that has not been touched in thirty years. A 16" should not be that much different.
I would say that you will be fine with the M7040 and 3 16s. The M9540 did great in 4WD with an International 710 with 4 16s, I did add rear wheel weights to reduce slippage. I was impressed with the performance. Here is a pic of the plow. Another pic using the disk. Sorry about quality. (cell phone)