To put a 318 into your truck would require a lot of custom adaptation and a whole new drivetrain, as nothing there (except maybe the t-case) would be able to handle a v8. advanceadapters.com is a great place to start v8 swap research. :thumbsup:
Also, when it comes to v8 swaps, the rule of thumb is, "just because the engine is cheap/free, doesn't mean it's a good candidate for swapping". I'm assuming from how specific you are about which engine you want to use, that it's already in your possession?