the common misconception when it comes to boost in a engine is the fact that everyone think it as stressful as running nitrous or big compression N/A engines. I have boosted a lot of engine most of them being the ls engine 4.8l/5.3l/6.0l boost is easyer going on yur rotating assembley. Prooven fact.
how ever the ls engines do not like rpms when it comes to the stock rods and rod bolts. the rod bolt will fail 1st. the rod being second. theres a lot of playing factors when it comes to a ls engine and there h limites and tuning has everything to do with it. you can take a forged assembly in a ls engine and it will blow with no problems with a bad tune. be sure to spend some money on a quality tune on a dyno and you will be in better shape.
the way most people build a 5.3l on a budget for boost is to do the fallowing things.
Arp or katech rod bolts. I have arps in mine but katechs are better and the price shows it, lol.
piston ring gap, you need to widen your piston ring gap on both the top ring and the second ring.
head studs and ls9 head gaskets. head gasket run from $100-$115 and arp head stud are about $300-$350 and the are 2 different types. one has 3 different lengths and the other has 2. I depends on the year of the motor
the 5.3l was know for a head casting 862 that had a notch and would leak coolant because of the notch. some people have the notch welded then milled, while other just buy a different head all together..
your fuel system is another big factor. build your system to the hp and fuel you plan on using. E85 requires a but more fuel than any other. you can aslo use meth injection to help with IAT temps and to make up for injector size. if a fuel pump claims it will support 1000 hp on forced injection remove about 35% or the hp rating for E85 so you would get 650hp out of that same pump in a boosted app with e85. while meth injection can turn 93 oct pump gas into 110 oct depending on the kit. I use both along with a large intercooler.
I did all of the above in my fbody and about 4 custom cars and we have easy hit 15psi. I have ran as much as 18psi with out a problem but knew I was pushing it.
fallow the above mods and find a really good tuner and you wont have any problems. most engine builder want you to spend the money to build the engine with top notch stuff because they don't want to risk the chance of someone blowing a motor they built and then trying to come back on them, UNDERSTANDABLE. but that also how the info get out there that you cant do things like build a 800hp ls motor without spending some seriouse money and that B.S. and I prove that everytime I go to the track.
the really nice thing is when my engine finally lets go, I can run to the junkyard spend $500 on new engine swap all my go fast parts and then im go out and spank cars that have far more money in there cars and when something breaks in theres, there out 10k.
hope that helps