I agree with the XG-91 recommendation. If practical, mounting on top of the 80' structure may buy some precious improvement in noise margin.
I advocate grounding the coax and the mast primarily for the purpose of improved safety to people and property.
http://forum.tvfool.com/showthread.php?t=901
With an antenna connected to the coax, grounding the coax shield will suppress channel 10 at the tuner in no significant way. Moving away from the ground block in either direction, there will be a point of high impedance every odd quarter-wave-length for any given frequency (assuming the ground block has an impedance of zero ohms, which it won't in practice). The signal from any RF source will still produce standing waves on the outside of the coax shield regardless of whether a grounding block is used. Standing waves on the outside of the coax shield will be decoupled at the balun / matching transformer, preventing them from significantly influencing the center conductor and shield inner surface. The antenna will receive vastly greater amounts of energy than might leak through the coax shield or balun decoupling. Without some type of inline filter to block channel 10, that energy will be coupled into the coax and delivered to any tuners connected downstream. As an analogy, grounding the coax for the purpose of suppressing strong or interfering signals would be like caulking a nail hole in the wall with no roof on the house... expecting to see the heating bill drop.
An inexpensive and effective method of suppressing channel 10 would be to insert a UVSJ. The antenna would connect to the UHF port, a termination resistor would be installed on the VHF port of the UVSJ and the common output of the UVSJ would provide minimally attenuated UHF signals and all VHF channels would be attenuated 20 to 30 dB. The previously mentions AP4700 would accomplish the same thing.
To specifically suppress channel 10 will require a tuned channel filter. Sources such as TinLee.com would be one possibility. The
CM5080 Channel Master Join Tenna would be a practical consumer grade option. It would connect in a manner similar to the UVSJ, the antenna would connect to the 'All Channel' port, the 'Channel 10' port would be terminated.