If you're talking about selling a shortblock with 83k miles, maybe $1k, if the longblock, maybe $2k. The complete engine with all accesories maybe $3k. A '04 longblock with 23k miles sold on NLOC for less than $2k recently.
Be specific, is this complete from intake plenum to oil pan, including starter, alt, exhuast manifolds, etc, or just a bare short block. I know someone right now that is asking a fair price of $1000 for a stock shortblock with only 30,000 miles, and know another who sold basically the same thing a year or two back for $650. So hate to be the one to break it to you, not really hehe, but I think your getting your hopes up, especially with over 80,000 miles and has been modded and raced... Stan