Well, I just heard back from the second mechanic. He concurs with the
first mechanic. The engine is toast. His opinion is one of the PO did
one or a series of valve job(s) adjusting the valves as though the van
had solid lifters. His opinion is that I should replace the 1.9L with a
OEM 2.1L (new: $5000 installed w\ 6month or 6000 mile warranty; used:
$2500\installed w\ a 90 day labor only warranty). He was very vigorous
in trying to dissuade me for purchasing any type of non-OEM engine, says
in his experience heavily modified motors don't work out in the end -
more problems than they're worth.

So, the choices under consideration are:

1) 2.2 GoWesty engine (delivery time 6-8 weeks; about $5000 installed)

2) New OEM 2.1L engine (delivery time 1 week)

Still confused,
Sam