What is the best practice to Transfer ledger balances across ledgers

Summary:

Requirement: 1.GL ending balance transfer from source primary ledger with GBP currency to target primary ledger with USD currency. The source ledger will be decommissioned after yearend.

2. The balance in target ledger needs to be shown as opening balance.

Questions:

1. Whether the transfer ledger balance process can be followed for this scenario? If yes, then how the balance looks like in Target ledger. What will the currency for entered balance in target ledger?
2. If this activity needs to be happened during year end, then which period is ideal for doing this activity, so that the transferred balance will be shown as opening balance for period 1 of new fiscal year?