Migrating old world files to new Gazebo Sim

Hello there, Respected Roboticists!
Does anyone have some tips for migrating a world file that was generated for Gazebo classic to make it work in Gazebo Sim?
I am having a difficult time trying to migrate the models meshes that were used for the Gazebo classic since the uri tag is different now. What I found is that I need to look up for the model online for Gazebo sim and use the URL in the uri tag but it’s really troublesome. I am sure that there is an easier way or some kind of a converter or something Or is it best to rebuild the world in Gazebo sim and save it?
Thanks