A. Any 1981 to 1983 Virago swing-arm will be the same, including the shaft driven 920. They use a mon-shock rear suspension.
From 1984-on, XV700 and up Virago models, there were no significant changes to the swing arms and they will fit in a direct swap. They all use dual outboard shocks. 
The 535 swing arm is totally different than the larger bikes, being some 4" longer, and having a different connection to the final unit. 
Comments: In a 60mph collision, when my '85 XV700 was hit from behind while stopped, the frame was damaged but the swing-arm and drive line was not. So be aware of the need to check the frame and drive unit thoroughly for damages if there is damage to the swing-arm. 
Additional Information:
Conversion to use the 535 swing arm on the '81 to '83 Viragos is possible, but could be expensive due to the substantial drive shaft differences in length and mating gears in the final units. Unless you're creating a chopper or some other custom, I'd recommend against it. You can contact me with through Virago Tech or in an email for more details.