As stated above by Bruno, most of the content of the forums will just "magically" move to the new platform.
What you are proposing is not even in the scope of what I would call a "migration", which is the term for "I wan't the exact same content in another system".
Migration are purely technical, it's just a matter of saying "we call that a box and they call that a container, let's have a tool which copies the contents of boxes to containers".

The issues stem from the fact that SRP is more a community and less a forum. Yes, you have a forum, and that's easy to migrate, but the community has added flowers and a goat next to the boxes.
And on the other side, they only have "containers".

Can your goat be assimilated as a container ?
For the flowers, do we use one container per flower, or one container by species ?

These are more, I suppose, the kind of questions the admins have to answer