Need assistance with a shopping list to convert '68 GTS to 73-76 center link

power steering box went to large spline in 73 I think the manuals stayed small.
check with Firm Feel they offer both large and small spline pitman arms.
https://firmfeel.com/collections/1973-1976-a-body?page=2
there may have been large spline manuals for C-body’s, truck and vans. I don’t have a pic But the plate on top with 3 bolts is clocked differently then the small spline ones