> There is a real possibility that one of the valves will drop onto a
> piston and cause much more damage.  You pay your money or you take your
> chances.  I would recommend new heads.  Many of the rebuilt heads have
> cracks.  The incremental additional cost is a small fraction of the
> total cost.
> 

My understanding is that NEW 1.9L heads are available only from AMC Spain. 
The 2.1L heads I get from Volkswagen are new, but even Volkswagen's 1.9L
heads are rebuilt.  I have been hesitant to recommend the AMC heads because
of the poor reputation of AMC's Type 4 heads; I wouldn't want to test them
on a customer before trying them myself, and haven't had a need for them
myself.  (And now that I've replaced my '85 with an '89, I can't see
needing 1.9L heads myself in the forseeable future.)  So I have not tried
their wasserboxer heads.  Has anybody had experience with them?
-Ron Salmon
 The Bus Depot
 http://www.busdepot.com