Nova is the same as the first generation Camaro ('67-'69) the 60" wide rear is getting hard to find because they are being bought up by Camaro owners. The '70 up Camaro rears are 61" wide and have different spring perches. You want a 8.5 10 bolt rear out of a '72 to '76 Nova, Apollo, Ventura, or an Omega as they all had the corporate ten bolt with either mono leafs or multi leaf rears.
Big Dave