I have some of the old Pre Ban 15 round original Marlin Plastic ones. They made them in 25 rounders also.
Anything that fits the 795s will work also. I think Promag even makes or was making some 70 round Drums for the 795s that will work. I use the Pro Mag 25 rounders in my Papoose and my 99M1 and 99M2s also.
Now in steel that is differant.
EDIT: Sorry I was not thinking right. The steel 12 rounders I have fit my Old 56 Levermatic. So in steel I have really never seen one over 10 for the Papoose and 795. I guess.
If you are not completely stuck on Steel for some reason. I have had very good luck with the High Cap Promags.