There are "standards" if you will from a PM perspective. I don't think I can help you with specifics other than to suggest you browse any of the books on proj. mgt. related to IT. I think the rule of thumb is 80% productivity without factoring in automation. Certainly skillsets and project complexity will vary the productivity .
I think the DoD has resources that discuss this in the RFP phase of a project. You might try looking at Hill AFB.