Fixed full choke will not do well with jacket sabots.
SX1 full - any full choked SG I would not shoot slugs out of , be they Brenneke's or the Lead 1oz.
Rifled barrel, designed for sabots, is all they are designed to do, not worth a flip at pellet loads, not versatile at all.
Smooth-bore is versatile Modified or IC , I lean toward Modified for Slugs and Serious SG use.
Nu-Line has the parts, for SX1 and Model 12s. They can also make parts for Winchester guns.
Nu-Line most likely has a barrel, and it it were me, I'd get them to install their excellent external knurled chokes on one. I would leave the original barrel alone.
SX1s come in Field , Target and Winchester Custom Shop. Field has the blue mag tube, other two have chrome , never cared for the chrome, some of us had Win put the blue one in to replace the chrome, or have the Custom shop do it this way.
Wood varies of course...
Tulsa show- fella knew what he had, fella wanting it knew what it was worth, Field grade $500.
Target Grade with two barrels fellow stole this for $750.
I plopped down $150 for a LNIB SX1 so a fella could buy a Benneli to run and gun. Being a nice guy I plopped down $135 for LNIB Model 36 he so he could get a black gun to match his shotgun.
I dunno, his family bought him these guns,I figured the family wanted someone to appreciate the guns, since he was not, and I would, I plopped down the money.
Being even nicer, I took his money at a tourney with a '74 SX1. Maybe he should of bought a more expensive Benelli, or something to help his shooting...
Value - depends on buying or selling. Everyone has their price they say...I'll take:
$1Million in Gold for my retired Field Grade 1974 SX1, 28" barrel [It was fixed Mod originally] with the Nu-line installed external knurled chokes, original owner's manual, and I'll even toss in an extra "O" ring , and bolt handle for it.
SX1 -Finest Semi Auto Shotgun - Period!