[Kokatha man]

Hi Jinxsta - don't know the gs-280 but if it's 12 volts and you replace the 8 "C" cells (which as you know are 12 volts) with a 12 volt 7aH battery you aren't changing anything at all except the capacity to deliver current (amps) for a longer time - called the batteries "capacity" - which is the ability to deliver any specific current for an amount of time (much longer with the 7aH battery.)

The voltage stays the same (12 volts) and hence the current draw of the motor(s) is the same - having a greater battery "capacity" does not mean the bigger battery will push more current through the motor - there is absolutely no need to limit current (your "amp amount") - it will not "fry" the motor, current (amps) is a product of voltage applied to the load, generally called resistance, the "load" being the motor. Voltage divided by resistance (in ohms) = current (in amps.)

Your only concern would be having the motor running whilst you have this larger battery "on charge" from a battery charger - and even then it would only be a problem if the charger had a very unregulated and high output voltage. Take this as gospel from an ex tech/electrician.