Classic/Antique Car Repair: 1965 Chevelle v8 283 oil leak, rubber gaskets, freeze plugs

Question
I have a newly restored, by me, 100% stock chevelle malibu. The original V8 283 still purrs like a kitten, but recently it started leaking oil. I have replaced valve cover gaskets and the intake gasket, but still leaks badly. Engine only leaks when the car is running. I am thinking the freeze plugs maybe. The oil seems to be coming from the passenger side rear section of the engine.

Any ideas?
E

Answer
Eric;
Hea-well as far as the freeze out plugs thats why thay are called that they freeze and pop out, so you should have no oil from them.If you do than you got some troubles. I would use some good rubber gaskets. clean the heads off good, use some silicone sealer just on the  valve cover side part let it set up than put them on. make them snug.
You know it could also be comming from the distributor washer.