Come on, man....Take a step back and read what you wrote.
You want to change either the K member or the entire front suspension just to keep an oil pan that is poorly designed. That is like buying a hat that is too small and then going to a surgeon to have your skull size reduced.
Can you fit Fast Ratio steering arms in and still clear the headers? If so, they are about 5/8" longer than stock and would clear your pan.
The 71-72 K members do have a slightly different steering box mount angle and the center link reflects that. A 66-70 B body K member would have the right angle but I doubt it would clear that sump. The welds do look nice but the sump should have been about 5/8" further forward or slightly smaller to clear steering linkage. Is this a custom pan? Did the builder ever actually test fit it in a car to ensure fitment?
A 6 quart HEMI pan and a windage tray clears everything and is far more than adequate for all but dedicated, hard core road racing.