Connecting rod balance problem.

[Kello]

This problem is for a Yanmar diesel, but any input will be appreciated.
I'm rebuilding my 40 yo Yanmar 4JH2E and found that the connecting rods were originally installed backwards (p. 2-19 of the Service Manual if you have a 4JH2E, 4JH2-TE, 4JH2-HTE, or 4JH2-DTE).

My engine has severe vibration problems, and now doing this rebuild I think it may be due to the connecting rods being installed backwards.

The big end of the connecting rod and cap have notches for the bearing, which lighten that side, and the opposite sides of both have some extra metal cast in that would compensate for those notches. So the big end is unbalanced.

If I installed the connecting rods the way the service manual says they should be, then the big ends would be heavier on the opposite side; if I reversed the caps then the big ends would be balanced.

Regardless, reversing the connecting rods would mean that the wrist pins would be "backwards" for either the piston or the connecting rod bearing, depending on how they were re-installed. (sigh)

So far no reply from the major US Yanmar dealer or the Japan headquarters. ANY help / ideas appreciated !!!