The newer K3 has 6 injector drivers and 3 ignition drivers.
So the injectors could certainly be run as you wish, but not really any point due to time running the 2nd set sequentially imo.
As regards ignition sequentially could be done if running 2nd set of injectors grouped but again imo little point with the kind of revs cossie's get to.
Still there you are your choice.
If you already have an earlier ecu, it may be possible to upgrade, depending on how old to K3 spec, would need ecu details.
tabetha