if the IP address stays the same then it's as simple as making backups of the Management and Log Server, installing SMC to the new machine and restoring the backups there. For reference see http://help.stonesoft.com/onlinehelp/StoneGate/SMC/5.8.3/SGAG/SGOH_Backups/Backi ng_up_and_Restoring_System_Configurations.htm. On a sidenote all the configuration is included in the Management Server backup so store the backups somewhere safe.
If the SMC IP will change then it's a bit more complex as firewall rules are needed to allow control connections from the new IP etc, see http://help.stonesoft.com/onlinehelp/StoneGate/SMC/5.8.3/SGAG/SGOH_Reconfiguring ManagementCenter/Changing_SMC_IP_Addressing.htm#XREF_16351_Changing_IP. If the IP will change then if possible it's best to do the change before moving the SMC.
In either case if you have the Log Server on the same machine and want to move the logs too, that can be done either by including them in Log Server backup (maybe not the best idea if there are several gigabytes) or moving the log storage manually. In latter case you can just take the /data/storage folder and move it to /data folder of the new SMC (replacing the existing storage folder). /data/storage is the default log storage path, act accordingly if you've set a custom path during installation.