Check up above by the valve cover and cam seals. Oil will take a circuitous route down the front of the engine and it’s not alway apparent where it comes from so if you can see the leak higher up on the engine, it may not be the front main seal. Just have to get in there and clean it all. Only other way to confirm is to put it in service position and take it all apart which is not that hard, just time. About a couple hours of taking things apart. That way you can get in there and see everything once the harmonic balancer and timing cover are out of the way. Then take some parts cleaner and scrub away.