318 oil leak

I have an oil leak in my LA318. It is coming from behind the harmonic balancer and I'm assuming its the seal behind it? It's making a mess and leaving a small puddle of oil every it sits after driving. I bought the engine from some dude on Craigslist and other than this leak the engine has been fine. Is there any other spots back there that it could be leaking from? Any suggestions or tips on repairing this? I fairly new to this type of work and try to research as much as possible before I learn the hard way...although sometimes its unavoidable. Thanks