Planetstrike and Stronghold Assault

Two of the Battlezones presented at the back of the rulebook, I was looking at them because my club in considering having a small event based solely on them.

What I'm looking at though, is the missions offered, and "The Armies".

Both say "The Power Level of the Attacker's army should be greater than that of the Defenders", but don't specify by how much. 1? 10? 100?

So, I ask you, what do you think?

What would be a suitable set of Power Levels?
And how could that be translated into points for Matched play?

If it helps, we usually play 2000pts, and don't bother with Open or Narrative at all.

Thanks.

(NOte: I'm aware its been rumoured that Chapter Approved will include expanded Planetstrike missions, but I'm asking in th meantime because I have this event to set up).

Soooooo.............anyone have any thoughts on this?

I played one of them, where you have to kill the other completely.
We played it more as a narrative thing, so I think we made some small adjustments.
A rather large discrepancy in points is fine, depending on how optimized you make your army for the scenario, around 150% of the points worked for us. But depending on how you build the table I think you could even go up to 200%.