Certainly there are constitutional rules around provincial representation or distribution, and those would have to be respected and would have to be met. Most of the common proposals that are floating around, however, would not violate those distributional principles, provided they were in fact taken to account, which I assume they would be.
The other kinds of constitutional limits include making sure that you provide effective representation and meaningful participation. Those are standards that the Supreme Court has outlined in its case law. Again, I think that most of your standard proposals for reform would in fact meet those constitutional standards as well.