In your standalone.xml file, look for this element:
<socket-binding-group name="standard-sockets" default-interface="public" port-offset="${jboss.socket.binding.port-offset:0}">
The port-offset attribute lets you modify all the ports wildfly uses, by adding the number you specify.
For example, the default value is 0, which means that http port will be 8080, remoting 4447, etc.
If you use ${jboss.socket.binding.port-offset:100}, http port will be 8180 (8080+100), remoting 4547 (4447+100), etc.
So you need to change the offset, nothing else.
EDIT: You can also do this by using a system property at startup, check http://www.mastertheboss.com/jboss-server/jboss-configuration/configuring-port-offset-on-jboss-as-wildfly