I think you would be better off getting another used motor, but that is just my opinion. I came up with a couple searching on shopping.google.com for a little under $500. Depending what is messed up now, it may not be worth while to reuse your engine as a core. I wouldn't get the rebuild kit until I had a machine shop look at the major components and get an estimate of how much labor to fix and what is still reusable. Usually a locked up engine is pretty trashed.
Pete