Yes you can use it on either CAN bus, the main consideration when doing this is the address the Plex unit is using. The dash does restrict a couple of address ranges on CAN 1 that are used with various MoTeC to MoTeC comms.
A list of these addresses can be found
hereWith the RPM conflict just select another RPM channel (Engine RPM 2 for example) and then go to Tools>Edit Channels, select the RPM channel and then click edit. You can then change the name to whatever you like.