ok, I'm thinking about doing a ground up rebuild of a 71 Charger and I want to put the largest motor possible in it.  Anyone know what i would need to know to pick out the best one?

any and all info is great...thanks  

How about a 540 indy motor?
Need to know? that the dyno sheet isn't fake[ your not building it yourself]  

Is money an issue?
If not the Indy 540 is a great way to go as mr. 4 speed has pointed out.
If your looking more for a factory set up a 440 is a great way to go, or a 400 with a stroker crank which will give you 452 cubes, you can obtain 500 plus horse power from either combo by doing nothing more than a good cam, headers, intake & 850 double pumper carb & intake with a good electronic ign.