Jonathan,
	1) rough running, oily plugs. 
a) Did you change points and condenser? Cap and rotor? Can you check 
	the point gap and distributor timing again?
b) Is there soot in your tail-pipe? 
c) Has this been since a particular fill-up? Might be bad gas, water, etc.
d) The old plugs you put back in- are they oily now?

Oily sounds like quenched combustion- bad spark, bad gas? Could also
be leaking valve seals and actual oil, but that should show as
some oil consumption AND some oil smoke (blue/white) on starting.

	If you want to know how the engine is doing, do a compression
test and look at those recently re-installed spark plugs, and
check the valves.

	2) Spark plug lost in engine tin.
I've done this :) I've got one of those grapper-snake gizmos- four spring 
steel jaws at the bottom of a flexable spring/tube. Thumb button and two 
finger hooks like a hyodermic. I wouldn't make a habit of leaving
spark plugs in there but I don't think you'll melt your engine
because of it...

	Good luck! And of course, let us know what happens!
	Bill