is the oil pan sealed up well? how about the rear main, was the 'spring' inside of the seal that applies pressure to it around the crank? I could see that as poteinally popping out, I filled mine with grease pre-installation to prevent that. Its VITAL that its installed evenly too.
There really is nothing other than the rear main and oil pan on that side of the engine that could potentially leak, unless the block is cracked or something.
My rear main when it first went bad would literally lose 4 quarts of oil in a day, they leak very fast and bad when they do leak.
I think you can use a special dye to add to the oil to look for leaks with a UV light, I had a pesky leak on the rear head somewhere that drove me nuts and it turned out to be a cam seal.