Hi Ken,
I replaced the Banner with a Xtreme AGM Battery item number CYLA30LXTA from our local Batteries Plus store. I picked this battery because it’s dimensions fit into the existing space without modifications.
Couple extra notes. I placed thin cork under the top cross plate to secure the battery better. Also if you use this battery, use the longer of the two bolts supplied and use two washers for the negative terminal and one washer for the positive terminal. That will be self explanatory when you install it.
I think too much attention is paid to CCA Sportster, which after all is only a laboratory achieved figure on a brand new battery. Of course you need current to turn over the big pots on that engine but battery capacity (amp hours) are needed to support that current. A battery will gradually loose its capacity over time, that's a given, so better you have a greater reserve in the first place. This will at least help support the somewhat academic advertised CCA. Furthermore it's only capacity that will offset natural current drain if the battery is not used for extended periods without charge.
The capacity of the premium priced (nearly three times that of Yuasa) battery you recommend, at 28 a/h is actually less than the OE battery, generally accepted as marginal at best to turn over the X- Wedge in the long term. Even my 850 Guzzi V twin back in the 70's had a 32 a/h one, and it didn't have drain from an immobiliser to contend with.