Not sure about ICAO right now, I'm pretty sure they have such stuff - try looking in their catalogue of publications.
Years ago the FAA produced a document that had a formula that could be applied to various different configurations to determine a theoretical capacity. From what I recall the capacities that it came up with were not always particularly accurate (give or take maybe 10% or 15%of what could be achieved in reality depending on the circumstances) but it was very useful for producing comparisons of different configurations when planning.