Completely concur with the above post!
Having been on both boats and owning one of the former, I dont think you are going to find any appreciable difference in headroom on one versus the other. Im 6"2' and I dont even notice being close to the coachroof and I usually boat with a hat on. The entrance to the aft berth on the 336 once through the hatch is at least 6'3 maybe even more. So dont let headroom drive your decision IMHO.
My pitch for the 336. 97% positive. ONLY negative is it is a big sail and they did not make in mast furling for it. We have a stackpack. Things that stand out for us. Fast boat, big hi roach main which is great in light airs. Huge cockpit. 8 easy in it. Powered correctly with the 27 horse yanmar. My friends 356 has the same motor and the rpm needs for same speed is significant. This motor will bail you out in the 336 if you need it. Engine access on all four sides of motor, to include the packing gland under removable panels in aft berth. ALSO the entire back wall in berth is removable. Allows easy access to rudder, holding, and fuel tanks.
All in all, the 336 only made for three years is great bang for the buck. Not to mention little things like slip rate differences etc. I have millions of pics, projects, etc, if you want any other info on the 336. PM or whatever.
Cheers