NEW engine and trans

hello guys new to the forum. i have a 99 Tahoe LT 5.7L 2wd. and i'm looking for a fresh motor to drop in and trans. can anybody point me in a good direction ie website and just general info...
I will be doing some light towing with the tahoe... thanks for the help....

i would go for the 6.0 Liter V8
but you got to make some alterations to the Engine bay

or go for the 5.3 V8 not as much torque as the 6.0 but more economic but dont for get to add a Transmission Cooler because towing make transmisson go to hell and back