Make sure you get them for the correct water pump. The car is a 1968 with the short water pump and smaller bolt pattern. The kit you linked to shows a 1969 which would have come with the long water pump and bigger bolt pattern. I believe OPG or Year One supply these pulleys.
I think your pics came out top and bottom not side by side.having said that I am pretty sure the bottom one is a long.I will defer to GM as to bolt pattern been to many sleeps for me on that
