Thanks everyone who have weighed in on this issue.  So far I have flushed
the cooling system, replaced the oil cooler and a fresh oil change.  I took
it for a test last night late to stress it a bit to see if there would be
new oil migration into the coolant.  The good news is that there seems to
be no oil in the coolant now!  I will flush again today and add distilled
water and coolant.  I think I am only getting about 50% of the coolant out
of the system when I drain it.  Any advice on how to get the maximum amount
purged from the system?

It is running rough on start up.  I also changed the plugs which looked
fowled, but as I bought this bus after the overheat issue, I have no
baseline of how it idled and ran before the incident.  I will be calling on
your wealth of knowledge as I proceed, but want to express my gratitude to
all of you who have helped out on this, and on all the
other panicked  situations over the years.  It is good to be back on the
list!

Best,
Finn  87 Pooh and 89 Roo