I had a simular problem with a type 1 vw.  I was perplexed for a couple
months.  But I finally found out what the problem was when I got the guts 
to rip the engine apart.  The main bearings were worn so bad that when
I grabbed the fly wheel, I could pull it back and forth an inch or two.
So that was my problem,  the movement in the crankshaft was causing the 
pistins to move and the rings would leak.  It came down with the same simtoms
you described. I hpoe this helped and that this is not your problem!

Jeremy Berndt 
<jwberndt@csbsju.edu>

PS- does anyone no of a list for Type I VW's?