I don't think their are specific regulations about forklifts, only what is covered in general under whatever regulations cover secure loads. The ruling is normally made by an MTO inspector at the scale. His or her idea of what is secure will vary. Anything that heavy (on wheels) is a potential big problem if you don't do it right. Forget about load bars and straps, it needs to be properly blocked and chained. The old days of burying it amongst some heavy skids of freight wont fly anymore.
If it is moving local, I normally tell my customer to call a tilt and load tow truck or their forklift company to look after it. The risk vs reward is pretty slim if something goes wrong.