Here's a drawing of the new arm you will need to weld to your rockshaft to move the cylinder to the rear lower left like a 1980 PK;
The arm gets positioned at a 90 degree angle to the lift arms that are welded to the outboard ends of the rockshaft.
I remember you saying something about leaving the OEM lift bar that now rotates the rockshaft, in place. ??
If so .... then I would attack this new arm this way > Fasten a bungee cord to the top of your existing rockshaft arm & pull it to its forward most position (as in fully lifting an implement) ... with your cylinder now affixed in it's new rear lower left position ... FULLY extend the cylinder. Mark with chalk, your spacing from the side of the bearing block (A) (1-7/16") ... to the side edge of your new arm (B) which you should have prefabricated & have in hand. Pin the new arm to the Fully extended cylinder & position it against the rockshaft ... to the chalk mark & see if it puts the new arm at a 90 to the outer lift arms ©.
It may be more or less than a 90 ... but I would say to weld it on at a 90 if you can. This will prevent your lift arms from ending up at some funky unusable angle.
BTW You will see in the drawing a lift arm measurement of 2-1/4" from the center of hole to the shaft .... keep in mind that this is just where the arm meets the shaft ... you will need this arm longer to cut in the radius so it fits around the shaft a little for welding.
Total length of the arm should be around 3-1/2"
Making this arm longer & adding more holes will give you more lifting power (by moving the cylinder pinning)... but shorten your lifting travel
Just tips to keep you from looking at measurements & cutting plates too short.
Another tip .... Use good deep penetrating weld on this new lift arm to the rockshaft ! It WILL BREAK OFF IF NOT WELDED PROPERLY !
(don't ask me how I know)