Very much depends on how much $$ you are willing and able to commit to the project. Frank06 can fix your head. Check with him for repair cost vs. replacement cost. As Yblocker said, depending on condition of your block, you can just replace the piston with a decent used piston and fresh rings (after you hone the cylinder - lightly). You will also need to replace the rod bearing. Check it with plast i gauge for clearance. Check the ad section, you may find a used head for not too much money with a cam and lifters for even less $$.
Personally, I would stay away from a used engine. Would rather fix what I had (because I can know what I have). A used engine generally is a pig in a poke as far as knowing the history of use and/or abuse the engine has had.
I have chosen the used piston route on a 96 Passat in my garage right now. When we measured the block, it was in great shape in all 4 cylinders. The crank was also in great shape on the two rods I pulled to inspect. Just put 2 new rod bearings, measured clearance at between .0015 and .002 inches, so good to go. Keep the Rods you have as a matched set. Another rod will have a much different weight.
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