In your original photo the engine mount is the problem...

Look at the photo and pay attention to the right arm of the mount... as seen by a pilot...

It is angled OUT at the engine. This means that the mount was set with the arms too close together at the base.
When you mounted the engine you effectively added more right thrust than that provided by the firewall.

You need to always make sure that the mount arms are parallel to each other and perpendicular to the firewall, before you drill the engine mount holes.