If you've got a garage, or just storage space for when you're done, Getting your own lift (unless your friend is going to really help you with the work too..). Harbor freight sells one for about 200, which is about what you'd pay for gas. there and back, possibly less. You also would have the ability to work on it at your pace, not be rushed to get the swap done in a weekend, etc.

Anyway, as Klaus said, the amount of engine damage/cause of overheat will determine the best course of action. If the friend doesn't know what happened but its still drivable, check for milkshake. Odds are it'd be head gasket, but there are many other causes. Find out as much info as possible. The head job is roughly 500 machine costs plus all the labor. Engine will cost less, if you pick your own, but you won't know its history, so there's risk there. Lots and lots of labor with a swap.

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If you're not driving it "like its stolen," are you really driving?