Chrome bumper: Bare crossmember from an eBay advert
Two upper pads AHH6205 each side with a collar round the bolt-hole that protrudes down into the crossmember, and two lower pads AHH6206 each side that are flat as there is no space left for a corresponding collar to protrude upwards.
Detail from the above showing collared uppers and flat lowers both front and rear.
Rubber bumper and V8: A stout channel has been welded on top of the original upper surface of the crossmember, which is what gives the higher front ride-height, as can be seen in this very clear image from Broad Arrow Classic Cars.
Two upper pads AHH6205 each side with a collar protruding down into the new channel piece, another AHH6205 each side at the front, facing upwards, underneath the original top surface of the crossmember, for the lower pads. Rears staying with flat pads AHH6296 in the lower position each side. Incidentally I'm assuming the V8 should have this arrangement as all V8 had the rubber bumper crossmember. The Parts Catalogue doesn't say so, but then it doesn't say 4-cylinder RBs had the different pad arrangement, until the 77 and later catalogue.
Detail from above confirming that the fronts changed to collared uppers and lowers while the rears stay with collared uppers and flat lowers.