I have a GM Performance 350 crate engine rated at 300HP. It has 30,000 miles on it and runs strong and true. I just put a new water pump,starter ,platinum plugs,alternator in to it. It is a four blot main with one piece rear main seal and center bolt valve covers the only thing it needs is a oil pan seal and timing cover seal. I wanted to sell it because I wanted to upgrade. Anybody have an idea what it might be worth? Any help is greatly appreciated!