So you want a manual RWD? Get a 320i with a nice lightweight 4 pot up front for sharper turn in! With close to 200hp (I’m taking the stats above with a large pinch of salt) it’ll be no slouch getting to 60 in around 7 secs and should handle better than the M340i (which will have the extra weight of AT/Xdrive/6 pot!!)
If you must have more power try 330i RWD which will get to 60 in around 5.5 secs (if you can live with AT obviously) for me an M340i AT X drive is not even an option... I’d probably get the imminent X4 (for better practicality) instead!!
BUT... as I said, I’m taking the stats above as pure speculation as in honesty I doubt even BMW themselves have actually signed off all the engine/tranny configurations yet!! The car doesn’t even go into production for at least another 8 months or so... anything can happen between then and now!