This gives a rough estimate, to get an idea of what to roll for: https://ravenholdt-tc.github.io/
For example, on how to read the sim info, one would need a 940 Specter Of Betrayal to get a slight upgrade over a 900 Convergence Of Fates, in the default profile.
To get trinket weights with your current gear (w/o having the trinket to equip), you will need to pull the trinket IDs from wowhead, and substitute them into your Simc profile.