Welcome, I'm an old school chip off the Oldsmoblock so not an LS expert but there are oodles and gobs of information here about the LS dos and don'ts you should find handy. I personally would ONLY want fuel injection if going to an LS swap or just throw an Olds 350 in it but that's me. Also, others can tell you whether the stock 5.3 bottom end is sufficient to turbo if you are planning on much pressure? It may well be, I just don't know? And, I know from experience when I temporarily put a 125HP Nitrous kit on the factory 307 [9] engine in my 442 that, oh it woke it up nicely, but it is a complete PITA and frankly dangerous if you are going to street the car much at all, and I am absolutely confident the 307 would not have lived long had I continued.
Just some things to consider . . . welcome!