http://themeparks.about.com/cs/usparks/a/othernew2004_2.htm
That article doesn't say anything about central Indiana. But this one does:
http://www.negative-g.com/Entercitment/garfield1.html
So here we can talk about what could have been, and what could be done with the land.
BTW: In the second link, it shouldn't be too hard to figure out the coaster at the left side.
And here's a topic from 2007 about this and the Old Indiana park: http://www.KICentral.com/forums/index.php?showtopic=9986&st=0&p=164004&hl=garfield%20amusement%20park&fromsearch=1entry164004
In my opinion, this park would have had been popular. If you look at Holiday World, it's not near any major roads as far as I know, and they are adding two multi-million dollar rides in a row.