With a SMPS charging a capacitor bank. What is the power rating of the SMPS?
I'm not sure where you got the idea that the power output determines the topology.  Power output can affect the topology, but unless you're working on something itty bitty, or absolutely huge (compared to my hand, to put it into engineering terms) the step-up or step-down ratio, the voltages involved, and whether you need isolation or not has greater impact.

You probably want a flyback*, and you probably don't want to think in terms of power output per se.  You want to think in terms of the allowable current on your flyback transformer, because charging a capacitor from zero to some way-higher-than-source voltage could otherwise put some wildly varying currents on your inductor and switches.

You do not say what capacitance you are trying to charge to 240V in one minute, but from your quoted power levels I assume you can't use an off-the-shelf supply.  Were I in your shoes I'd start with some white papers on photoflash units and extrapolate upward in power from there.

* but at a 10:1 ratio you could maybe get by with a buck-boost.