My suggestion is using just a single buck or a single boost, with the obvious limitations that the buck can only achieve 2*Vin.
For 144V, where one would need voltages higher than 300V boost would be a better topology, but still a viable choice for 300V inputs. Again, the inductor only handles half of the output (the negative mirrored portion).
Here is a paper describing such method
http://www.ti.com/lit/an/slyt286/slyt286.pdf