Thanks all for the quick replies and hints.
I went ahead to see whats possible.
Made a 7 parts casting mold with the waste mold process , waiting for each part to set and separate with mould release then proceeded to build the next part of it up by hand, it is not for perfection anyways, not expecting the form to be perfectly like the master, going to do rework on it adding additional elements as well as smoothing it out when the slip cast dries out completely with a smooth sandpaper and smudging it by hand.
So all this was about is not using excess amounts of plaster because of the shape of the master. could have just built a large box around the whole sculpture, but i would end up having a mold that i could not even lift up let alone slip cast. Have to wait 2 weeks for it before it dries, so i will let you all know how the casting went.
Thanks
Simon