Battery connector swap between iPhone 7 and 8

I am looking into the possibility of switching the battery of the iPhone 7 into the iPhone 8 to lead to longer battery life for the latter. Problem is, the batteries have different connectors in both. I know that the battery connectors can be repaired/replaced and so switched as well.

Could someone please outline the process for switching the battery connectors ? Did you switch the connector on the motherboard or the battery itself ? I suspect the iPhone may not accept a smaller battery than it expects but if you place a larger one (like iphone 7’s inside an iPhone 8) if might work. Also would it be more prudent to switch the connector at the end of the wire or the wire itself ? I would expect that switching it on the motherboard itself would be a much more arduous and failure-prone method.