how I'm lining things up. Differences between a 68 J3000 frame and a 82 J10 SWB frame are minimal in the front. Some holes are the same but not many. The threaded bumper bracket holes are identical (circled in red)
basically I'm using the center of the rad support and the center of those threaded holes as base points since the front clips are the same 63-91
Newer shock towers will bolt on with two of the holes for proper sweep back positioning. 3rd hole will need to be drilled or likely just a weld at the bottom.
The recessed areas on the 82 are the holes that Tad uses for the steering brace IIRC, as one can see, that doesn't exist on a first gen frame.
It looks like GEN2 motor mount arms for I6/360/401 years would bolt in fine with the addition of one hole drilled.
Brake line brackets and bumpstops would have to be added as well, all in different spots.