my 70 gauge cluster mounts to the back side of the cowl/firewall by two at the top and one on each far side outside the round perimeter to the steel dash. all that is concealed by the pad when mounted. other than that you have the three screws at the top of the front of the cluster to the pad.
the passenger side is just three at the bottom on the underside/front and three to the pad at the top of the cluster.
since you are changing from 69 to 70 there is a difference in the alt/brake/oil lens on the tach. if you are into it that much then you might want to check into it. 69 says brake system and 70 just says brake. nothing big but it is the details you are changing. if you are uncertain then go to
www.tachman.com and look at his 69 shelby setup. i am taking it that you have a deluxe tach. i just got my set in the dash myself.
a new set of lens is a world of difference. amazing at how much clearer everything is.
jeremy