Poboy, a couple of things...Do you have a conventional dual-gage leakdown tester? If so, what were the actual readings (like 95/100 or 112/120, lbs air pressure in vs lbs sir pressure held)? And even though it is a bit of a challenge, each cylinder needs to be tested at TDC or you won't get good readings. The ratio of the two readings is your percent leakdown. Rick is right that the leakdown tests only the sealing of each individual cylinder...rings, valves and head gasket. Additional note, a leaking exhaust valve can be heard as a hiss through the exhause pipe(s).
Secondly, if/when you pull the intake, check the ports for
oil. If you have
oil on the walls of the ports in the heads but not on the mating intake runners you almost certainly have an intake gasket leak. If the intake and ports are dry (of
oil), you've got something else going on...bad valve guide seals or rings cracked or not seated.
Let us know what you find.