Found this great turbo spec calculator, thought I'd share it. You can drop down and get the factory specs for a 5.7L hemi (says it's for a charger.magnum but it's the same engine). It'll get you a very good idea of what turbo you should look for.
http://fuindustries.com/MKIV/Spreadsheets/MKIV-Turbo_Calculations.xls
http://fuindustries.com/MKIV/Spreadsheets/MKIV-Turbo_Calculations.xls