My 02¢.
Yank the current one out, and toss an equivalent one back in. Not all that difficult if you follow the instructions laid out in a service manual that you can find on this site, or better yet a book for your truck available at most auto parts stores.
Once it's up and running, take the old one that's sitting in the corner, put it up on a stand and rip that sucker apart. By then, you should have more confidence and knowledge (due to research) and rebuild it the for the goals you are trying to reach. Maybe get it bored and stroked, new rotating assembly, cam, heads etc.
This forum is great at spending others $$$$, but the knowledge on here is priceless as well. Lots of guys/gals have done what you want to do.
If you are uncomfortable doing the work on your own, reach out to someone in your area via the interwebs, church, classifieds, Goodyear blimp or however you can, and see if someone is willing to mentor you through it.