What  Mods if any will be needed for my 1999 Tahoes swap-out to a 383 or 4" stroker kit & the OBD-2s fuel needs? Thanks for any help.  

If you want upper rev range performance, you'll have to include a larger throttle body see BBK and others. http://www.bbkperformance.com/products/throttle-bodies.shtml

The computer will have to be "reprogrammed" see these guys

http://www.fastchip.com/

http://www.hypertech-inc.com/

http://www.superchips.com/

http://www.kcspeed.com/

http://www.jetchip.com/

Bogie