can your rack accomodate the vk-60 (~17"x24")? i've yet to find a non-custom "rack" large enough, although i have seen dedicated amp stands that worked well. also, the amp is pretty heavy for a top shelf. why are you opposed to having it on the floor?
another option: i have my vk-75 on the floor resting on BDR cones and pucks...allows adequate ventilation underneath and isolates the amp from vibrations.
another option: i have my vk-75 on the floor resting on BDR cones and pucks...allows adequate ventilation underneath and isolates the amp from vibrations.