It depends how aerobically deficient you are. Do our HR drift test and out AnT test and see for yourself. If you are not suffering from ADS then by all means do this.
You may find that the aerobic base helps your boxing.
If my reading of history is correct, a lot of famous boxers used to log many miles/week of easy running. It is not specific to your event but it is supportive of the anaerobic work and will allow more hard training and faster recovery.