Importing open Projects as part of go-live

Anyone with best practice recommendations would be very welcome.

We are implementing OneWorld, with Advanced Projects (aka Project Management).  We are also using Revenue Commitments which means all Projects must be associated to a Sales Order.  We also need VSOE allocations and the Contracts module, which aren't really relevant for this specific problem but indicate the level of complexity and impact analysis required for every implementation decision.

For a number of reasons, actual project management (resource allocation, assignment, task progression, etc) will continue in the legacy system and NS will be used only for billing and rev rec.

We have 200 open fixed-bid projects on milestone billing schedules at varying stages of completion.  The current method of rev rec for these projects in the legacy system is % completion, therefore I could have a $100,000 project with $25,000 billed and $50,000 recognized.