Welder series Makes weld it yourself Hot rod components. Their catalog and web site, U tube video's show how to install their pieces, It is a good reference to use when installing a stock M II crosmember like yours. You might be able to pull the wheels, get a string, plumb bob. level and start checking all the pieces on yours, Your car is down in the weeds. does it have dropped spindles? . Usually when one is that low the upper A arms are above the frame rails. There are kits to Bolt in custom M II crosmembers. That would have been the easiest way for the original builder. The upper A arm spring pocket Might have been welde in too low. Those old chevy Frames are not as sturdy as other cars. I would have used a long plate with the strut rod bracket welded to it, then weld the plate to the frame. I have seen some frame bottom piece start to buckle when welded like yours on the frame. a 6 to 8 in plate would give more weld area, spread the load along more of the frame.