A guy I used to work with road raced his pinto, I think some of the guys in his class custom built tubular Upper A arms, 1 in DOM, chrysler screw ball joint sockets They were more of a wide U instead of an A shape. It might be easier for the new owner to Buy a new bolt in crosmember, cut out the stock one and use His pieces, The Mustang II stock crowmember probably should have been notched to get it the right level position, It looks like the spring pockets are still factory welded. My son still has the pieces to put a stock crosmember under his 36 plymouth coupe. He looked at a car last summer at a car show and said the guy had built a couple wedges to go between the stock crosmember and the frame to get IT Right. The chevy front frame rails are fairley straight, the ply dodge cars hump up the frame . If the original builder just C clamped the stock crosmember to the frame everything started wrong. Frame should have been at ride height and rake. then the crosmember adjusted by notching or wedging make everything plumb, level, square, take it apart and grind or sand blast the crosmember weld area both sides inside and outside of the weld area, hospital clean, I have seen stuff welded where the other side of the metal was coated with grease and crud, hard to get a good weld welding in greasy mud contaminating everything, . tack, recheck, tack recheck.