Find the source of the leak first. I had a leak on my thermostat housing that showed up on the back of my oil pan. Don't go rippin' and tearin' till you find the source.
Ditto on that,it ran along the inlet manifold where it joins the head and then down the back of the engine.
If I remember correctly the SBC has one behind the flexplate/flywheel.
My friends '52 developed 'incontinence' and he traced it to that one.
As far as I can remember he repaired it with the motor in,just removing the trans to access it.