It’s not possible to have a full-wet reverb on one path that only sends to H90 output 1, and a dry signal on output 2. When using Insert Routing, the physical input/output connections determine if the algs run in mono or stereo, or mono in > stereo out etc. Most of the algorithms have predefined L/R panning, with the exception of some newer algorithms that have panning parameters.
You can use parallel routing along with a mono or stereo insert to tap the signal path and send it to output 3 or 4, with or without FX processing.
Some examples of wet/dry routing are shown here: https://cdn.eventideaudio.com/manuals/h90/1.5.2/content/setup/wet-dry.html#wet-dry-examples
Since the ACS1 can run different amp/cabs in the L/R channels, I think using each side as 2 mono insert’s in the H90 could have some great results.
The best thing you can do is experiment with different configurations and see what you like.
