Never heard of anyone doing it, but to go from a power stroke to an octane burner, you're going to need to do a lot of work. Flushing or changing the fuel tank and lines, probably better off going with the change, fuel pump change, transmission may need to be change, it's a little more involved with just changing the block.
Why in the world would you want to ? Your way over your head in this one. Even if you did manage to get it swapped in how are you going to find suspension parts to down
grade the 7.3 to 428 ? The 7.3 weighs 1050 - 1100 lbs. The 428 weighs about 650 with all components attached and maybe 330 H.P. If you don't change your suspension your
front wheels will feel like they are welded to the frame which could actually crack. Mind you, that is your choice. Good luck.