2 Q's - A leak and timing

[Peters02]

Hope all are having good holidays.  I am still working on my 72 w a 2bb 318 and have 2 questions:

a) I am chasing an oil leak - rear of engine - dripping from lip of rear pan gasket (the semi-circle part).  The engine has < 2 hours on it - rarely driven (as the car is still in pieces) - mostly started just to run it and tune it.  I have the pan off now - is there any way to tell if a leak is from the pan or the rear main seal?  I'd rather not change out the rear main if I don't need to.
Background - I did notice a drip of oil in the same spot when I was about to install the engine.  I figured it was just some oil left over from the rebuild...maybe it was in fact oil that made its way through the gasket and thus the drip now...I just don't know.  Any ideas?

b) I recently timed the engine w a vacuum gauge.  Once I got the vacuum to about 18 the engine settled down to a purr and I have no stumble on acceleration.  My question is as follows - the position of the distributor puts the vacuum advance right against the coil AND the timing mark is nowhere to be found.  Could I have this thing 180 degree off or the wires in the wrong spot?  (I did install the distributor w the rotor facing #1 cylinder)....

Thanks for all the help.

Peter 

[Chryco Psycho]

if the rear main seal was installed backwards it will leak , the only way to know for sure is to pull the cap
if you move all the ign wires one position you can rotate the dist 1 position away from the coil , no way you have it wired wrong if it is running , the outer ring of the damper may have moved which is why you have no timing marks

[elacruze]

Your leak can be as simple as an unsealed bolt hole, if any of them are open into the crankcase-I'd expect this is so if it had a drop before running. You can re-position the distributor by dropping it back in one tooth more in the direction it needs and re-timing.

[Peters02]

I will try the distributor tricks - thanks.

Regarding the leak - if I drop the cap, will I need to replace the seal? 
Just trying to avoid the risk of fixin' something that ain't broke.