The 5.3 doesn't have much more HP but it does have a decent amount more TQ stock for stock.

 

Last question... (hopefully). Does the engine in the link appear to be in good condition? Some of the parts look rusty... Is that normal? Basically asking for a visual critique. Thanks.

6.0 LITER VORTEC ENGINE MOTOR CADILLAC ESCALADE LQ9 64K DROP OUT | eBay

 

If the vehicle the engine came from was in an area with high humidity or in an area were they use road salt in winters then Yes rust and corrosion would be normal.

 

You can get a new long block for less than $2600 and all the missing parts will swap right over from your current engine.

 

All of the stuff I've read on forums, and off-road racing sites, plus magazines have told me any engine from 4.8L to 6.0L should fit in any silverado from the years 1999-2005 due to having the same engine bay space and due to having the same frame setup. In my old 2500 before I found out my frame was fucked we used to have a 5L engine in it then my dad bought at 6.0L .383 stroker engine and transmission and we dropped it in and flashed the PCM and then my truck ran perfectly fine. But just recently I found out about the frame and then today went to look at a 2001 1500 and found out that my engine and transmission will fit in the engine bay and it will fit like a glove. (Although some sites and magazines and close friends who build trucks for off-road and drags have told me you might have to change the motor mounts and such but it will fit.)
Thanks for reading.

 

http://www.ebay.com/itm/Remanufactured-5-7-long-block-1-year-unlimited-mileage-warranty-ls1-iron-block-/271034081966?hash=item3f1ae3e2ae
THompson is a sponsor here. All you stuff from your motor will transfer over to the long block.