I'm pretty sure if he really wanted to Bosa could gain the strength (adding pect muscle weight) to equal Watt's 34 reps. Whether Bosa could maintain (or exceed?) his current measurables with 20 more pounds of pure muscle? Who knows. Of course time will tell with regard to Bosa's potential and performance in the NFL.
For the heck of it let's compare him to Jaedeveon Clowney, who's closer to his weight. Clowney blows both Watt and Bosa away in straight line speed. Clowney also beats Bosa in long jump and the vertical. But Bosa beats Clowney in bench press and in lateral speed/control in both the 3 cone and the shuttle.
Here's an interesting link that superimposes the 40yd dash performance of Watt, Bosa and Clowney: http://youtu.be/XGZkkrQM1f0
MOD Edit: Updated link. Yours wasn't working. https://www.youtube.com/watch?v=XGZkkrQM1f0&list=PL4Yp_5ExVAU1YqPRofvFJjvKNkEB-MGJj&index=11
JOEY BOSA, Combine Grade 6.8:
HT: 6'5" WT: 269LBS., ARM LENGTH: 33 3/8", HANDS: 10 1/4"
40 YARD DASH: 4.86 SEC, BENCH PRESS: 24 REPS, VERTICAL JUMP: 32.0 INCH, BROAD JUMP: 120 INCH, 3 CONE DRILL: 6.89 SEC, 20 YARD SHUTTLE: 4.21 SEC
JADEVEON CLOWNEY, Combine Grade 7.5
HT: 6'6" WT: 266LBS., ARM LENGTH: 34 1/2", HANDS: 10",
40 YARD DASH: 4.53 SEC, BENCH PRESS: 21 REPS, VERTICAL JUMP: 37.5 INCH, BROAD JUMP: 124INCH, 3 CONE DRILL: 7.27 SEC, 20 YARD SHUTTLE: 4.43 SEC