Looking in the B44 parts books and getting this on pushrods: B44 GP
41-590. The same number for other early round barrel B44s. From engine number EA-101 (round barrel) 41-592 (0592). All square barrel B44s, including the 1967 SS and VR, used 41-790 (0790).
So I think Ratio's info on lengths isn't complete and that there is a difference in round/square barrel pushrod lengths, as Peter Quick lists.