ok, here is the deal, I built a 431(440 source kit and stealth heads) for a guy and I used the flat top pistons and stealth heads with minimal decking(only to clean and make flat), and a lunati cam .226/.234@.050 dur. by .494/.513 lift, RPM intake/thunder series AVS 800 carb, HV oil pump, deep oil pan, windage tray with felpro gaskets.
when I first fired it up, lots of oil leaks, pulled the engine and replace the cam plug, 2/3 of oil leak gone. Next, I pulled the oil pump and cut 1 coil out of the pressure relief spring, and replaced the gasket...still has 80psi, no change. And replaced both valve cover gaskets from rubber to cork, even better, now only leaking from the rear of the engine. Pulled the engine again, replaced rear main seal, and both pan gaskets using Mopar black ATV, new oil 10-30w (broke it in on 20-50w VR1)also redid the oil galley plugs with new teflon tape. Ran it for 15 minutes in the driveway car facing up towards the garage, and after about 10 minute it started leaking from rear of the engine, but very little (like the size of a silver dollar after 15 minutes).