Cylinder head oil leak help.

[matchstick321]

Well I just did my first automatic to standard conversion on my 79 k20. And after driving it for a couple miles and then bringing it back and puting it in my garage I looked underneath of it and found that it was leaking...
I fingered arround back behind my engine and as far as I can tell it's leaking from the back of the cylinder head.
I'm wondering if I should clean it up back there and try to shove some silicone in the leaking area? Or if I should just take the engine apart and replace the head gaskets?
It's a 350. So just wondering from any one with experience if it's hard to take the engine apart, how long it would take me to to the whole project. Or if you have tryed siliconing it, and if it worked?