OK< I was wondering if you had Edelbrocks, which tend to pool oil up in the heads a bit. A/J (I think) observed that the drain slots were higher up in them than stock. BTW, do you have a working PCV system on the engine? It looks like you are using pretty tall valve cover gaskets, and they might get pushed out of alignment pretty easily with crankcase pressure and cause a leak.
On the rocker shafts, were the mounting holes top and bottom 0.375" diameter? Any larger hole on the one on the oil supply pedestal, and one of the oil restrictions to the shaft will be gone.