SBC for truck
If you already do not have the engine /trans etc, I would check Craigslist, local nickel saver, local newspaper ads, etc. Maybe leave a note on the local machine shop message board as to what you are looking for. You can probably get a running or rebuildable SBC 350 for $100,00 to $400,00. In my area this is very common. I would try to get one complete with all brackets, mounts Etc. The small things will nickel and dime you to death! Even if you don't use some of the parts on the engine, you can sell them to offset your project cost. I have even purchased a non running parts car and sold off the chassis after I took the engine / transmission out for more than I paid for the car to start with. Great to get a FREE engine this way. Word of caution, never buy a engine without actually going and looking at it. I have found that "great condition" to one person, could be used as a boat anchor for another person.