I had sliced the model to try to reduce the number of supports needed and printed the model at original scale. Wasn't 100% happy with how it turned out but I liked the model and wanted a larger skull. I found that if I sliced it into three parts could scale it up to 144% which would make it a good size.
Supports used for all three pieces.
Raft for skull_bottom (the lower jaw) only.
Used ABS slurry to connect the pieces.
Used Meshmixer to slice the model into three pieces.