340 or 360?

The biggest gain between the two engines when going to a 360 is torque. The longer stroke produces more of it. The bore size is a 4 incher, plenty of size but a bit shy to the 4.04 of the 340. Most engine rebuilds go .030 anyways.

More torque ='s easier get up and go. More torque earlier.
A longer stroke engine tends to have power fall off faster at the big end of the RPM scale and it often drops quickly were the shorter stroke engine hangs on to the power (HP) for a while afterwards peak power, but torque falls like a rock.