I'm currently for an LT1 engine to rebuild. I have decided that instead of moding the LT1 in my Z28 I will just buy a used engine and rebuild the engine how I want it. I will still do minor bolt ons to the engine in my car and I will just transfer the mods when I do the engine swap. My question is what do I need to look for when shopping for a used engine? What kind of mileage do I need to look for?

Thanks for the help.