HaHa, big plans for that beast with twin turbos and stage 3 cam.
You can boost a stock bottom end but turn up the boost slowly while tuning and I wouldn't go more than 6psi on a stock bottom end personally. Some people go up to 8 maybe 10 on gen6 BBC but that's a different engine than your TBI block/heads.
I see you already have headers and an aftermarket intake, Are you running a carb or still the TBI? If carbed, you will need a blow through carb and a boost adjusted FPR.
While twin turbos right off the bat would be awesome and would probably get you to your goal but those can be added later after other engine upgrades if you still want more power. I would do it in stages... Put a cam of your choice in first, just know that there is a limit before you will need to modify the heads for lift. Maybe get a set of aftermarket heads or gen 6 junkyard heads and rework them. Get the engine the way you want it then add the turbo(s) after you tune and feel the truck with those first.
Remember turbos dont change the HP and torque curves, they just increase them.
