On the one hand, it sounds like you're going to have more in reapir than buying another one. On the other hand, it sounds like you have a sentimental attachment. Only you can answer the question as to if the sentimental value is worth the cost of the needed repairs.
From the sounds of things, I think you have a build project on your hands. That said, you know, if you go ahead with the repairs, you know you don't have to put another 4.6 in it, right? You may have to weld in new engine mounts and change or even delete the computer, but you could put a 351 Cleveland in it, or a Boss 302, they sky is the limit. Then back that with whatever transmission you want. A build project is an opportunity to make something unique. And not just in the engine bay, but body and interior as well. Do you homework/research and go nuts with it!!!
But, if it's eat'n tires, I'd say it needs to go back on the frame straightener before you do anything else.