People probably don't want to answer that because answering that is a bag of worms.

Boost is not a measure of load.

You're thinking power and torque.

And the first thing to go is ring lands. So if you gap the rings you're good for close to 4 digit numbers provided your valvetrain doesn't float, and the entire set up has to be dialed in correctly.

I'd suggest reading some books and if you aren't a reader really dive into some youtube videos about people building stock bottom end ls engine platforms

 

would it be hard or expensive to build a 5.3 to make 650-700 hp with boost on a stock bottom end

 

For 550whp realistically all you need is valve springs regardless of if you're using the stock cam or not, but of course that would be much easier and more fun with a cam. Personally I wouldn't go much above this power level with a supercharger on a gen 3 motor, but turbo... now that's a different story.

 

sorry for my ignorance, but what makes the strain on the engine different from a turbo and a super charger

 

The degree of control that exists against accidental ... whatever.

A turbo can get out of hand WAY easier than a belt-drive blower.

Not so much a matter of what happens in normal operation; more a question of, what can go wrong, and how bad can it get when it does.

 

Murphy's Law.... ol' Murph LOVES turbos......