Cams How do you choose one?

I am curious as to where that graph came from, and what engine it might apply to....?? The reason I ask is that it does not strike me as correct in general, but might be so for a specific engine and setup. So, forgive me, but I just can't subscribe to the above graph as generally accurate.

Example: My 351C was solidly in the torque band from 2000 to almost 6000 RPM and had a best shift point of around 6500 RPM. That was with a cam with .050" lift duration of 192 on the intake LOL. So its actual performance did not match up at all with the above graph. The modifiers that come to mind that may have moved that engine waaay off the above graph were:

• The very good 351C intake ports
• 1-7/8" headers with 18" collectors
• A gen 1 Torker single plane manifold
• Long cam ramps from .050" to .006" lift at the lifter
• The 351's 1.73 stock rocker ratio (a lot more lift versus duration compared to a 1.5 rocker ratio)
• 10.3 SCR and 8.3 DCR
• All on a 600 cfm carb

Edit to add: BTW, I generally think a couple of the trends on that graph are right: the rising RPM of the torque band with cam duration increases, and the narrowing of the torque band (ratio of the high to low RPM's) with cam duration increases. It is just in the absolute RPM numbers presented, particularly at the low RPM end of the graph. Again, I suspect this may more closely apply for one specific engine setup.