For a complete used engine, you can check out ebay or junkyards. Advanceautoparts.com, sells re-manufactured engines that include the heads, and it looks like it would be $1700 for the engine from them. That would still leave you needing the ECM, intake manifold starter and alternator. It would also be a good idea to swap out all the freeze plugs with brass ones before installing a new engine if it doesn't already have brass plugs. I bought my boat with engine problems too, had to swap the LT1 out due to water leaking into the oil from the #2 cylinder, but I was able to reuse anything I wanted to aside from the old block.