On my P235 I have a pole, supplied by Bill, which fits on top of the keel to stop it running back and bolts through the bulkhead. Obviously this means that it is not possible to lift the keel if you accidentally run aground, (one of the benefits of a lift keeler!). So I do not fit it for normal sailing around the Solent but do put it in when going offshore such as doing the Parker Round the Island. Due to the weight of the P235 keel (300k) I think it unlikely it could run back in a normal knock down and only if somewhat more than 90 degs. I did suggest to Bill that perhaps a peg could be inserted through a hole in the keel box in the cabin but he didn't like that idea at all!
As most of the ballast in the 235 is in the keel, I think it might have difficulty in self righting in the event of the keel running back in a total knock down. The manual does show all the calculations for the righting moments etc but don't know if this aspect is covered.
Jim Hamilton on Sandy lady has a pole fixed down with a lanyard and that may be a better idea than a fixed bolt through the bulkhead
Peter (P235 Zephyr)