The symptoms seem unusual. A remote possibility is that the engine was
flooded and the fuel washed the oil from the rings in those cylinders.
Squirting a little oil in them, spinning the engine with the starter and
then rechecking the compression would be in order. Also check for fuel in
the crankcase oil. Can't think of anything common to those two cylinders
unless they might be fired from the same coil or might be fuel injected at
the same time. Hope someone else has some better ideas.
Don Young

Dear Mike,

Zero compression is not good, even engines with scored cylinders will
create some compression.

I would remove the valve cover from the bank in question and check to
see if the cams are out of sync with the crankshaft <Chain jump> at
TDC. Next turn the engine until the cam lobes on the cylinder in
qustion are pointed upwards <compression stroke> and measure the valve
clearances. If the chain became loose you may have bent some valves,
if so you will have excessive valve clearance on the bent valves.

If you dont want to do the above....see if you can rent or borrow a
boroscope and look inside to inspect the cylinder walls and valves. If
the valves contacted the pistons you would see fresh marks on the
piston crowns and the valves.

Regards,
Blake Dodson