Should have LS7 cast into the block. Possibly in the bell housing area. The LS7 block is unique to the LS7. I can't remember the head casting number but the heads are also unique to the LS7. Dry Sump oiling while not unique is a dead giveaway to being a vette motor. If you do a Google search on the casting numbers for the heads, I'm sure you'll find them. Might even do a Google search on identifying the engine. Who knows, someone may have already written down all the unique characteristics to identifying an LS7.
Ok found a picture of the engine. Since you said it was a crate engine, it should look like this if it is a GM crate engine.
http://www.crateenginedepot.com/stor...Product_ID=930
Notice the exhaust manifolds are unique which I had forgotten about. The intake manifold is unique as well but is so similar to the LS3 that you need to know the difference from seeing them side by side.