Kind of confused by your last post, punctuation and all, but if your asking what size of stone I am no expert... but typically a larger/longer stone is going to make your life easier when it comes to larger longer blades, and it will accommodate smaller blades just the same. Really in my opinion anything is really feasible. I have used that smaller Smiths stone on my BK9, a 14 machete, or a spey blade on a stockman with no issues... Just takes practice.
Also higher end stones start costing a lot of green... are they worth it? ask those who use them. All mine came second hand. If you are inexperienced in sharpening with stones, start out cheap and work your way up as your technique and experience builds. If this does not seem like something you want to do, look into getting you a KME, worksharp, edge pro, sharpmaker, etc etc etc. But freehand sharpening is a very rewarding, relaxing, and fun thing to do. In fact taking a knife from dull to sharp on just about anything is rewarding.
So quick answer...
If you have no experience with freehand stone sharpening, I say learning how to is a life long skill that is transferable. Just takes time. Find you a stone or 2.
If you have experience, look at flea markets, antique stores, or online for a good level stone. The maintenance and tinkering forum here probably has a lot of recommendations on specific types of stones.
If you want results now or with a limited yet rewarding learning curve... buy you one of the aforementioned sharpening systems like the KME. You'll get a mean edge that'll be great for your KA-BARs.
Good luck!