The military board is hereby authorized to enter into an agreement or agreements with the township board of the township of Grayling in said county of Crawford, for the construction or repair of the public highways leading into and through the reservation, or to take over from said township any highway approaching or running through the reservation after its construction and repair by the said township, for such consideration as may be agreed upon between the military board and the township board. The military board may alter, straighten, or lay out highways within said reservation and improve such highways, using therefor any moneys to the credit of the military fund not otherwise required for military purposes.