First thing you can do is rule out the heater coore, or lose heater hoses as this is an oil leak, and they have coolant in them.
Second thing to do is clean ANY, and ALL sludge, dirt, oil, etc. etc. from the entire engine, transmission, frame, front supension, etc.
Then start it up and maybe see where its coming from.
Did you make sure the valve covers flanges were nice, flat / strait?
Did you use a high quality rubber valve cover gasket?
Did you thoroughly clean and inspect the valve covers for holes?
Did you inspect the oil presure sending unit to see if it was leaking, at the threads, or through the sending unti itself?
Did you throw away the end gaskets for the intake, and use a TOP QUALITY RTV silicone gasket maker? If not that would be the first thing I would suspect is those piece of crap end intake gaskets!