Honestly man, I think you're better off putting that money into a used engine. You might not know if one of those liners is loose until you get that engine up to operating temp.

I did the same thing as you: bought a truck with the same type of heat damage. A good friend of mine in the UK (user cuda2266 on youtube) and a friend of his finally talked me out of trying to rebuild my engine.

Search around your local area for a Land Rover Club. Usually, someone there will have a couple of parts trucks lying around, and might have a line on a running engine. Throw some headgaskets on that engine, and if you're feeling froggy, put some new bearings in the bottom end, toss her in, and go!