1.6g shouldn't be a problem for 2S, as long as yours have an extra Rx Tx for the GPS. I also wanted to add GPS on my 2s toothpick but the aio does not have extra uart for GPS. Are yours analog or HD?
@Forol1561 well Betaflight Just always displays the total number of possible uarts with each FC chip, so you will actually have to look and see if the board has the UARTs available to wire