I have a set of 120Y GX con rods & they are the same as the 1200 rods that I have. This is why I suggest looking at some late ones.

The rod on the left is from a B210/120Y GX with the small pin & the one on the right is from an A12A. The rods are the same length. While I never had problems with mine, you can understand that boring the small pin hole out will reduce the material around the pin.
While I can't prove it, I believe that the late A12 rods are made from the beefier forging on the right.
The pistons are A15. A used original & a new 'replacement' in second oversize. [77mm] It was intended for my 1200 block.