340 Vs 360

The 340 was Chrysler's "performance" small block from factory, giving it a reputation among some to be superior to the larger 360.

But IMO this is a misconception. Unless you are doing a restoration on an original 340 car I would recommend the 360.

The blocks are different

360 bore = 4.00"
340 bore = 4.04

The crankshafts feature a different stroke and main journal diameter, the stroke difference makes up the bulk of the difference in displacement.

This means a factory 360 crankshaft cannot be used in a 340 block. (not without substantial modification, anyhow)

360 Main journal diameter = 2.810"
273/318/340 main journal diameter = 2.500"

360 stroke = 3.580"
273/318/340 stroke = 3.310"

Both the 340 and 360 engines used cylinder heads with larger ports and valves than 273/318 heads.

For performance, the larger displacement of the 360 provides a clear torque advantage over the 340. Furthermore, the 340 engine is often more expensive due to limited production numbers and a result of it's performance oriented marketing history.