Making a new Pitman arm would be about the most difficult solution to this dilemma I could think of, and would still not solve the problem. Your problem is NOT the Pitman arm, but the drag link, or relay rod as you call it. If your hi-steer uses 1-ton tie rod ends (TRE), they will either have 7/8 or 1" threads -- way larger than could ever be mated to your OEM drag link. You need to have someone make you a new drag link that is large enough for 1-ton TREs (I use 1.375" o.d. DOM with a .375" wall). You can then either ream out the Pitman arm to fit a 1-ton TRE, or use a smaller TRE on that end -- like one that already fits the Pitman arm. Often on these custom steering setups you have to spend some time coming up with the right TRE for the particular configuration.