Salmon river setup.

I have used 6 wt flyrod and 8 wt fly and switch rods,not familiar with centerpin.More important is the reel,must have a good drag system.I would forget the surf rod,no fun with that!

Lots of us (40 years ago-before DSR) made our first trip to Sr and we all brought our salt water rods--big fish right?
When we got there the shops sold us pre-made 2 foot long  leaders with a #1 hook and a swivel. Also told to use those little green or red rubber eggs-to be legal and have something on the hook.
Everyone said - they don't bite and ya gotta snag them.
Then came the Martin reels with a nice drag and the 10 wt Ugly Stick. A common rig on the river then. Same leaders and "bait".
OH- those leaders used  about a 40 lb test mono and if ya wanted to you could buy those weighted trebble hooks and snag fish mid river just like snagging bait fish in Salt water.
Took a number of years- after the first indoctrination - to learn and go to real fly equipment.
Congrats jack - you are years ahead of what it was for me.
A nice 8 wt rod about 10 feet with a reel that has an EXCELLENT drag will do you well to start. Decent flies are easily purchased up there in all the patterns that work although egg imitations are a good starting place.
Also don't be afraid to use pre tied real egg sacs either- they can be killer.
Be sure and use a heavy wire hook in a size no larger than #8 ( imho) as thin wire hooks will quickly straighten with these fish- they can be bulldozers in the current.
Pickup some pink flies too as the Co Ho love pink- if they are around its a hoot as they fight great and on some days bite readily.
Jack- have used a 5 wt and a 6 wt but if there is any water or you are in a swift  current  they can be VERY hard to use with a 20 lb plus King fighting hard. Commonplace to have to bust fish off because the rig is light- its ok to use them and they can be fun but be good to yourself and start with an 8 or 10 during the learning curve.
Personally have settled on an 11.5 ft switch in #8  as it is so versatile.
In steel season I use a 5 wt.
( disclaimer- 20 fisherfolks will give 20 different opinions lol)( look for the middle ground)

I don't know what kind of budget you are working with but find an anti-reverse fly reel in the 6-8 wt range.  Yes the knuckle busters work but they hurt like hell when a hot fish decides to make a run back to the lake.  Lol  

I would leave the center pin at home.  Don't expect to get a 50 foot drift on the SR during salmon season.  I think an 8 wt in a 10 foot length is best for those that just want to invest in one rod for all things.