If you have the tools and a bit of remaining warmth, I'd leave the Head alone, and pull the Timing Cover. It's easy to do in an hour or so, it's all stuff that will need to come off when/if you do swap the motor. But you can find out relatively easily if that was your problem. If it is, well great, cheep fix and you're off. If you decide you still wanna swap engnes and go the bigger money route, hey no harm done right, but at least you'll know. I got my timing kit which had everything needed for around $100. As I said I've beaten on mine without any bearing changes etc... for over 10k. Purrs like a kitten! Anyhow, I'll let this one go now as it seems you really would rather just put in a new engine. I can undrstand that. Just let us know when you do figure it out, what the problem turned out to be.