2001 Dodge Caravan Help I have bought a dog

I am an idiot, total idiot. I bought a car at the auction, thought it was a bargain. In the cold light of day it's a total dog. It seems at some stage water has got into the oil and caused enough damage that you can hear the con rods banging as the car warms up. If this can be dealt with the rest is do-able although any hopes of a great deal are long gone. I may have to throw good money after bad. My options seem to be.

1. Just try to sell it for what I can and run away, not sure how well that sits with my conscience.

2. Fill it up with STP and see if I can get some useful usage before it explodes then scrap it. Any wild guesses as to how long before meltdown. Not too long is my guess. However if there is any evidence of a rattly old engine going on for a while it could be worth a risk.

3. Look into engine swap or rebuild. I don't really have the tools or knowledge to do this. Is it even worth looking into, any guesses as to a figure for this.

Yes I was warned about the risk of auctions
Yes I did go to just look not buy
Yes I did get carried away and bought the first one
Yes I am a complete idiot