Shimanos are the only spinning reels I use,
for river fishing...
I don’t see the need for 30# braid?
For casting and visibility, fluorocarbon is the bomb.
We’ve never snapped a mainline using 15# p-line,
and landed quite a few 20+ kings and 12+ steelies
If fishing the salt, it’s down rigger fishing for me, with a level wind Abu 5000s mostly
Loaded with 30# braid, but that’s for trolling resistance, not capacity or strength.
Off topic:
I also use 200# braid for my downrigger ball lines
Allows me to use 5# balls with very limited sway. And a high level of sensitivity.