Hi,
I fish the Orchy every so often (took my first salmon from there and 4 in 2 days last year). When it's right it's great. But that tends to only be the next day after a spate, it doesn't stay in condition for long.
Better angler's than me will be able to temp the residents when it's not in top condition no doubt.
I get my permits from Loch Awe Stores. This site is quite good for a summary....
River Orchy Fishing Association
Another alternative might be the Lochy up at Fort William. May be a bit more than an hour away but holds it's condition for longer being loch fed.
FishPal - Scotland - West Coast - River Lochy - Home
If you don't go expecting to catch great numbers and drink in the surroundings and take any fish as a bonus you'll love it. Good luck.