Yes, mags for a marlin M-70 work. I bought a 25-round banana mag today for the M-70 and it fits perfectly.
Now, I haven't fired it yet, lol...but it cycles rounds through manually...
This was were I got the tip:
http://www.hoosiergunworks.com/catalog/magazine_inter.html
@ Barret50cal - the brand is Champion, labelled as "25 round magazine" "Marlin model 795 & 70".
Yes, it took a tiny bit of wiggling to get it all the way up there the first time...but then it went. I think the folks online that say "795 mags won't fit" perhaps haven't "tuned" for their mags. It ain't rocket science (well, actually, I guess it kinda IS, lol)...but with the JW-14, you can SEE how the wood has just been gouged out by hand to make the banana mag fit - so no worries about shaving a TINY bit off to accommodate the 25-rounder.