How many TD passes will Dalton throw in his career?

[*ochocincos*]

I saw an interesting article on nfl.com talking about who between Roethlisberger, Rivers, and Manning will come out on top in terms of career TD passes and how many (if any) of them will break into the top 10 (article here: http://www.nfl.com/news/story/0ap3000000502885/article/eli-manning-philip-rivers-or-ben-roethlisberger-most-career-td-passes)

All three of these QBs have been playing for 11 seasons, throwing for 259 (Manning), 252 (Rivers), and 251 TDs (Roethlisberger). They all probably have (at least) three more NFL seasons ahead of them, so they will all likely break 300 passing TDs and crack the top 10.

This got me thinking...what is Dalton at and how high could he feasibly get to by the end of his career?
Currently, Dalton is at 99 TD passes, which after four seasons equates to 24.75 pass TDs per season. That average is higher than all three of the above mentioned QBs, but that average can be hard to sustain throughout the course of one's career.

I looked at the list of the top 250 QBs in NFL history regarding career pass TDs (http://www.pro-football-reference.com/leaders/pass_td_career.htm), and nearly every QB in the top 50 has played through at least 11 seasons. If Dalton were to keep up his pace, he would have 272 pass TDs after 11 seasons. Given his overall clean bill of health, he could have a long enough career that he could exceed 300 pass TDs.

Given all of the above, about how many career TDs do you think Dalton will have by the time his career is done?