Was the intake wet in ports 3&4, ie were they "talking" to each other?
Did you check the cylinder walls for cracks? Remember they can be VERY hard to find.
When my wall cracked (billowing white smoke out 1 side of a v8), I drove the rig almost 100 miles to a friends garage, tore it down & found the wall crack. Later on teardown, pistons & bearings looked so good I could have re-used them. I babied it, but ended up with about 12 quarts of oil+antifreeze in the crankcase - surprised things looked as good as they did. So you probably haven't done any damage down below, yet - but gotta find that leak!
