I need a little help on this one. Since I built this engine 7 years ago I could never stop it completely from leaking 
oil.
The problem seems to be (cheap) valve covers/breathers, 
oil pan gasket and/or front/rear main seal.
In order to adress the topside of the engine I ordered new fabricated aluminum valve covers with extra thick flanges, Fel Pro #1684 molded silicone gaskets and a breather tank that will connect to the valve covers with braided ss lines and AN fittings. That should do the trick, or at least I hope so.
About 4 years ago I already installed a new Kevko 
oil pan using a molded, one piece Fel Pro #OS 34508 R silicone gasket, but to no avail as it seems. While the side rails of the oil pan look rather dry the leakage seems to come from the front and rear part of the gasket, below the timing cover seal and rear main seal.
The timing cover also received a new seal 4 years ago (Fel Pro), as recommended I installed the cover loose and torqued it up after the balancer was in place to make sure it is centered.
I used the Fel Pro Viton rear main seal #Z2901 for this engine from the beginning. Installed it with the parting lines not lining up with the rear main cap parting lines, with a dab of sealer between the main cap and engine block. Everything was cleaned meticulously before assembly. 
It's hard to tell if the leakage is coming from the main seals or the oil pan seal.
What gaskets are recommended for the oil pan as well as the rear main seal and the timing cover seal? 
I finally want to find a solution for this problem as I'm really tired of having to clean the garage floor from oil droplets from a freshly rebuild engine after every drive.
-Simon