Yay!! Data! On my phone so it's hard to see what that curve says at an hour. 20min @255 corresponds to 242 FTP (95% of a 20 minute effort). Getting winded at 80-90% of FTP is what we've been saying. That would get you to the point where it's hard to talk as soon as you cross 190 and into the 200 range. That's normal.

Congrats. You have the same kind of anaerobic engine that I have. I believe that's what I called and one of my first posts. Assuming you can eventually get your weight into the 160 range you can be fairly competitive in cat 5 crits.