Conversion of historical Payables and Receivables transactions

This question probably crosses communities but i posting it here first.   Our client, despite our recommendations and cautions, insists on converting 22 years of transactions history while maintaining links to gl balances.  Their data is currently maintain in a subsidiary's oracle EBS instance.  The subsidiary is spinning off so a fresh install rather than an upgrade is underway.   The safest way to accomodate the clients wishes, to our knowledge is to convert all transaction history in detail, financial period by financial period; run create accounting and transfer data to the general ledger but delete not post the subledger journals so