If you use a Bluetooth BMS you can monitor the cells on your phone.
18-page ES thread
thunderheart recently posted some discharge curves for the GA; you should be able to estimate capacity from that. Look at the lowest-current curve and calculate capacity between 4.1 and 3.1 V, then multiply by your parallel count.
What is your application? Sounds like you're not using a controller, so is this just a replacement for the lead-acid battery in a normal gasoline motorcycle?