I don't use much overdrive and I don't stack other pedals (just lusting for a good compressor pedal), so I'm probably not going to be much help.
I would suggest that you just hook up the Opus without anything else and see what you can dial in with that, trying the different Preamp models at different Gain levels, and (optionally) Power Amp models, with a good Cab Sim (like the Standard Powerhouse 2x12 - purchased separately for small price).
The only preamp model that doesn't really do overdrive is the Gemini, but the others will go into OD at very different levels.
I suggest using the Custom EQ even if you only use the LPF and the 3K to 12K filter - to dial back the higher frequencies that can be harsh with OD.
After you get a feel for what the Opus can do, then decide on what you want it to contribute to the tone, as it can do as much or as little as you want, for instance, Cab Sim only, or Cab Sim + EQ only, really any combination of the sections within the Opus.
Hopefully, someone with more pedal and OD experience will chime in.
Also, you might want to ask the same question on the
2 Notes Opus Thread as well.