I have the same rod and agree that it is closer to an 8 wt. I have used a 540 and I recently bought a FIST 510 to try. Haven't used the line yet but plan to get some practice with it to see how it works.
Try a 500gr Beulah Elixir and a 10’ polyleader, 525 Tonic and a 10-12’ tip is good for a skagit.
The Beulah Elixir has awesome carry and turnover for touch and go casts. I used that setup on the Grand Ronde and really whipped up on them especially in tough casting situations. I’ve got a friend who swears by that setup on the Deschutes. 4WIW
Airflo skagit switch 540 GR. It feels like gear fishing but man o man will it chuck heavy tips and big ugly flies. If I had to swing up a winter fish to feed my family this would be my go to rig(except for a FIST line).
I’ve had one for the last 8 or so years. Great stick. I agree with several of the suggestions above but will add my $.02..... check out a 480 grain airflo rage compact. If I’m fishing light sink tips (80-90 grain) or dry line/poly leader type stuff, chances are I’m fishing a rage. Such a great match for this rod. Just flat out sings. I don’t enjoy fishing skagit heads on this rod very much anymore, I prefer the more relaxed casting tempo of other rods out there for skagit, but when I do I really like 510 airflo intermediate with 10-12’ tips. That combo has caught a lot of fish for me over the years and when I’m in the groove it throws great.
Before I fished an intermediate skagit, the 540 skagit switch was my go to. I’ve played with commando and airflo scout heads too but for me the intermediate skagit is such a hunter it’s hard not to fish it.
I picked up a skagit compact 540 from Big Tuna the other day, hand delivered. At the price,I couldn't pass it up and it was the wt someone else recommended. I appreciate any additional information and approaches though so keep them coming
I've got the same rod and it may be one of the best winter tip rods I've ever cast. For me, the Nextcast Zone FF in 550gr just flies (and turns over much more smoothly than typical Skagits), with any tip and any fly, no matter how gnarly. A lot of folks like the F1 as well but for me, it was just too much weight. The rod could handle it, I just didn't care for casting it. Haven't tried a dry line on it yet.