Pan gasket for 360. What one works best?

i believe it a two piece seal, and I am using a fel-pro pan gasket. using a light just right i can see up thru the back of the engine and i can see no oil around the rear seal area. I should have bougth a crate engine for what i have in this. but i have to much in this to quit now. runs great just leaks oil.

Well, then, where is it? How can something be leaking out the back of the pan and not be leaking out of the rear main seal area?