calculate motor size for rotating platform

I'm looking for an experienced freelancer to help with calculating the motor size to start and run rotating platform with an off-centre load for a public artwork. The platform is 500mm diameter. The centre of the load is largely on centre to the rotation, but mounts to the rotating disc 200mm from the centre. Th object weighs 70Kg. It needs to run at 8-10rpm and the motor needs to be quiet. I also need to create a safety stop mechanism in case someone gets caught up in the artwork. If you have the skillset to assist me with this project, I'd be very grateful for your help.