Thanks Folks!
We will check all valve clearances before proceeding. I will need to find a good engine shop in Medellín, Colombia, where we are for a while. The one where we discovered the low-compression cylinder is not communicating well, I'm losing my confidence. I'll keep y'all posted.
Dieter

 

The Toyota is now in the big Toyota dealer shop, called Autoamerica, in Medellín, Colombia; comparatively expensive, but best equipped. The engine is removed, and quite likely, we will do a complete rebuild.
Getting good-quality parts for the 3vz in Colombia is an issue only in that it may take a while... but I have more time than money (or sense? : )
Still, I'd like to explore what it would take to get the parts from the US. Colombian customs is a huge PITA, but it could work with a freight forwarder. I've surfed around a little bit for rebuild kits, etc, but would appreciate your recommendations... all of them, including those about the 3.4 swap. Far as I know, the 3.4 is not available in Colombia either; the 4.0 is.
Thanks!