If you can PM me, I’ve got a number of leads for you on ammo and / or brass, but I don’t want to violate the forum rules by naming or promoting retailers.
6.5X52R (Rimmed) ammo and brass works, if you can find it, unfortunately anyone that shoots .25-35 very much knows that, so it’s also hard to come by. Don’t confuse it with 6.5x52 Mannlicher-Carcano (rimless) ammo
All that I have found is pricey, but if you find some, bite your lip and snap it up. It’s all getting harder to find, from what I have seen.
I load .25-35 with a 117gr Hornady RN (#2550) bullet, pushed by 21.5 gr of H4895 & CCI large rifle primer.
My old ’94 loves this combo, so I do too. The '94 was given to me by my father-in-law before he passed.... he was an avid Winchester collector.
Lee full length dies and Classic turret press. By pure chance, I found an over-run on a Lee factory crimp die. I made a Lee Case length gauge using a 30-30 length gauge that I chucked up in a drill press and carefully filed down to .252” dia. I used the drill press because it was too small to chuck up in my lathe. It’s .004” short, according to specs, but better a little too short than too long. I've never found a commercially made length gauge for this caliber.
BTW, as Arizona Griz stated, your 94 was manufactured in 1908. (ser # 430985 to 474241)
Check this website for serial numbers: http://oldguns.net/sn_php/windateslookup.php