That is a great work area for a project like this. You could leave the truck running as-is and get a longblock together. Then swap it when you’re ready
There are pros and cons to building a used motor vs building a new motor. I’ve had good and bad experiences both ways. If new, buying a bare block $900, bare crank $200, oil pump $500, etc from ford. There are a number of cylinder head deals out on eBay, Send the heads off to head games for GSC springs and retainers, SI valves is my plan. then have a machine shop bore/hone/clean/assemble with gen3 crank and there are options for bearings, pistons, rods valves as you see in the aftermarket. I’m planning to do a deep dive on all that at some point
If you wanted to start with a salvage motor, I think a 2021 Lincoln Navigator is probably the best starting point. It may have the updated gen3 br3z phasers lifters and rollers (but not the guides or tensioners). Also You can learn a lot if you take your time during engine tear down.