I assume you are talking about a stand-alone RADAR Mark? If so it doesn't really matter, as I don't think the GP7000 will display the RADAR screen or show an overlay etc. Some hig-end integrated RADAR systems can detect and dodge targets (with Autopilot) but in your case this wont be applicable.
Your S1000 could communicate with other Raymarine products via 'SeaTalk' (or something like that), and your GP7000 probably by NMEA0183 - or it may also have NMEA2000 ports, however that would only be to display speed or position etc. With a stand-alone unit I don't see the point in hooking them up.
cheers
Brendon