It’ll happily sit on its keel (..though ours is a 33, not a 331, but it won’t do it any harm).
Beware, though, of rough water “bounce” ..you wouldn’t want to sit on the bottom in, say, Dagenham Dock when a huge ship – with a huge wash – is going by!
But on a slowly, gently ebbing tide, with no churning wash – you’ll be fine.
(We’ve sat on ..the same patch of.. sand outside Dunkerque when I’ve (twice!) misjudged the tide by 10 or 15 minutes, and I’ve sat on the sand outside Ramsgate when I had to wait for something or other (can’t remember what).
They’re SOLID boats, and I’ve sat on the keel in boatyards when waiting to be hauled in or out.
If you’re intending to lean against a wall, ensure that you’ve more weight on the WALL side of the boat than on the ‘free’ side, so that she’ll be sure to lean the right way! Put your tools and kedge on the ‘wall’ side deck, and run a line from the ‘free’ side to a bollard ashore on the ‘wall’ side so that she can’t possibly tilt over the wrong way.