Every
oil leak on a SBF always ends up on the block plate. It always looks like a rear main seal, and often is not. Could be something as simple as the
oil pressure sender port, or the damper pulley.
Go to NAPA and get a dye kit. Fleuriscein dye for the crank case, and a black light. Clean the engine really well and let it dry. Put the dye in and let it run for a few minutes. In a dark garage, look all over the entire engine with the black light. Keep doing that until you find the leak.
A local mechanic here in CO has a leak detector. It's a simple machine that makes an
oil based smoke. Plug it into someplace simple like the dip stick tube. Where the smoke leaks out is where the oil leaks out. Finds the leaks in about 10 minutes.