every ls motor i have ever peeked inside of the IAFM is an oily mess, thats how they roll
Kinda that's the point? Aggressive driving/severe service (aka high rpm romping) aggravate LS's infamous oil consumption issue.
Did you look at your old 5.3's throttle body yet? I clearly saw oil running down into intake from passenger side valve cover. Don't even need to open the throttle blade.
Quick search on pirate 4x4 say to cap passenger side valve cover port and throttle body port and for the PCV there's few options I found;
1) install a catch can and vent to atmosphere & cap the PCV port on top of the intake manifold
2) install filter on driver side PCV port to vent the crankcase and cap the PCV port on top of the intake manifold
3) install a catch can/oil separator between valve cover port and PCV port on top of the intake manifold.
I will do option 1, to keep oil from running into intake for in case a roll over should occur.