I was debating the same thing and after checking prices and asking alot of questions I decided to go with a GM Crate engine (LM1). It turned out cheaper and this an all new motor with a 3yr 100k mile warranty. Here's a link to the place where I just bought mine..
http://www.lowcostengines.com/1067353.htm
Their prices have gone up slightly since I bought mine since I paid a little over a $100.00 less but it's still a good deal. Best thing is now there's no more oil leaks and she runs real smooth!!