Voltage Regulator vs Buck Converter
When you are dealing with automotive power supply design, there are several factors to keep in mind. 14V truck battery is not just 14V, but it can increase upto 24V if directly connected through ignition. Also the ignition time generates a high current which is first problem to worry. The whole power supply design can be divided into stages. 

Stage 1: Protect your PCB from current surge with appropriate PTC fuse.

Stage 2: Use buck converter having appropriate rating (5V/1A in your case, so choose 5V/2A for further current distribution) (Heat sinking/thermal distribution is important point here in PCB design)

Stage 3: Input this 5V/2A to linear regulator to obtain 3.3v/600mA.