Topband: Feeding vertical

[Merv Schweigert]

I just bought an old AM broadcast site with two towers,
they are tuned to 870KHZ and spaced 1/4 wave apart.
I shut the station down this week, and wonder if anyone
has an idea of how to simply feed one of the towers to
try it on 160.  They are 300 ft from the shack and I have
hardline run to them, just like to try one until I  can decide
what they will be used for.  On 30 acres with 120 radials
under each tower, close to salt water. 
Any simple suggestions?    Thanks  73 Merv K9FD/KH6