Need correct Pitman arm

I don't know if the later center link will work on 1 gen' a-body.
Does your idler have ball stud at both ends like 67 model?
I remember reading that Firmfeel or some aftermarket vendor offered a custom pitman arm for this mismatch but I never looked for it. I sincerely doubt a similar "bastard" idler arm is available.
So if the later model center link fit and solved the pitman arm issue you might still have a idler arm issue. Solution would be to weld a different clip on your K member for the 73 up through bolt mounted idler.