How high does your model require any elevation to be?
In the interests of making a working model of the flood even if not supported by evidence that it actually happened, if the sea floors where at 0 elevation the watter would cover everything to a hight of 2,6 kilometers.
That is of course Rough math calculation because if seas experience a slight centrifugal effect do to the earth rotating so the same amount of watter covers a higher elevation at the equator and a lower one at the poles. The watter kind of flows uphill sort of because of the centrifugal force. If the earth would stop rotating and everything else remains the same the oceans would gather at the poles revealing a dry land around the equator.
I have a moddel that could make the flood possible.
The earths core is heating up the material inside the earth causing flows that push the earths crust in an outward direction from the center kind of the same way the sun dose it when it goes red giant. Now if some magicman or chance would introduce material that brakes/slows down nuclear reactions i think they use graffite in nuclear power plants the force at witch the hot flowing material pushes against the crust would be lower causing the earth to "shrink" a bit unleashing devastating cunamies and floods, raising and lowering of land, that could be described as a worldwide flood. If someone could introduce material that slows down nuclear reactions or if some nuclear material at the earths core that was providing a boost where to run out this scenario would be plausible but it still dint happen.
Christianity, One woman's lie about an affair that got seriously out of hand