Some things to keep in mind.
Both 23m and 24m /26\ SKSs were of the same high quality.
Both should have the 'French Tickler' handguard. (difficult to find if it is missing)
Both should have the inverted takedown lever, which should make you want the original stock, or at least one cut for the inverted takedown lever. (very difficult to find at all, extremely unlikely to find without a serial)
Both should have the III symbol on the sight leaf to be correct as well...these are also kind of hard to locate.
These features are found primarily on these year models, and should be what makes you want one as close to original as possible. The inverted takedown lever/stocks only also appeared on some M21 models, and the phenolic/bakelite handguards were only found on these models.
I am in the final stages of restoring a 23m. It took quite some time to find a stock, and I had to settle for one that was cut for a side scope mount...but at least it is blank. I had to hunt down a blank magazine, and find the correct color handguard for the year model. (23m had a slightly darker color than the 24m) It was kind of cool to find a date stamped 78 sling for it just by coincidence.
These are very well built, no cast parts...the only drawback is the stamped trigger group as far as top notch quality being used on these. Some love the handguards, some hate them...some only like them because that is what is supposed to be on them. (like me) Unfortunately, due to the somewhat funky nature of them...often over the years owners would discard them for something 'else'. Having an incorrect stock is only a big deal when you jam the lever under your thumbnail due to it being flush with the stock on a 'regular' cut SKS stock.
They are unique with all these features vs. the more common Chinese SKSs out there, and generally will bring a slight premium if collectors are aware of them for sale. Usually the handguard is the frequently used LOOK HERE portion of the listings for them. That may help in your search for one. Searching for French SKS should narrow down searches...sellers rarely specify the factory.
IF you can find one, 25m /26\s are also of the same build quality...but return to the wooden handguard. These are very very rare though.
Intersting choice for a first SKS, if you already knew all of this stuff...I applaud you for knowing what you want.
Oh yeah...and welcome to The Files