The bolt pattern changed in 1970, when the aluminum water pumps with the longer snout and passenger side inlet started. It's not your 73 balancer that is different. It has the standard 70 and up pattern. Your best bet would be to find a later set of pulleys in the configuration that you need. Bouchillon Performance in SC sells every kind of reproduction Mopar pulley you can think of.
https://www.bouchillonperformance.com/