Those should fit, if they're authentic. I suggest adding a little lubricant if it's a tight fit, and I'd bet things will loosen up over time (hopefully). Just be gentle as you try to wriggle them in there, so they don't get stuck, or anything else bad happens.
I really hate it when mods are a tight fit for batteries, it's so much easier to damage the wraps, so I would keep an extra eye out for that as well.
Best of luck. I believe I remember reading a thread where a member was experiencing the same issue, with a different mod and was looking for batteries that might fit. I think the consensus was that the brown LGs are slightly tinier (we are talking small differences) in their specs, but I don't know if those batteries would be powerful enough for your application, and since my memory is spotty, I'd also try to see if you can get the exact dimensions for those batteries (if you feel they might work in your setup). Sometimes 0.5 mm can make a big difference in a mod like that.
Best of luck, I hope you get a resolution soon!
Anna