Direct swap, but I need new engine mounts right?

 

I would put new mounts on it. It is easy to replace mounts when you are swapping motors.

But to your question, the mounts are the same between the two motors (2.8L vs 3.4L). The 3.4L shares the same outside block dimensions with the 2.8L.

 

No!
The 3.4L is a 2.8L bored out to create more power.

 

The 2.8 3.1 and 3.4 are all the same engine family. Im glad you mentioned the 3.4 as an option! I was thinking about rebuilding a spare 2.8, but now considering a 3.4!