Its not rocket science, the 5.0 has a larger displacement and higher compression, so yeah they produce good power, with or without mods.
Can they live with boost, I'm sure. But I wouldn't trust one to run as long as a similar factory terminator motor. Most high boost high hp coyotes have had the internals replaced and built. (Even the OP claims a built motor) They may not have done anything witht the topend as I'm assuming the heads/cams flow well, but the fact that people have to already build these motors to handle the boost shows something IMO. I dont' remember many terminators building them when throwing 20lbs of boost years ago.
And saying terminator motors aren't reliable at 700-800 hp, well depending on tune and how the owner treats it, yeah it could go. But the fact that some actually live at these levels without grenading the motor is still pretty amazing.
And while while some (due to owner or tune or both) may be living on borrowed time, with proper cooling mods and tune they last much better than other cars. Which says something.
And regarding the comment about being better handling, quaility, yadda yadda. They come with coil overs, even stiffer/optional suspension upgrades on top of this, and panhard bar. It handles better I'd assume to this more than some kind of magical chasis.
All the talk of well put a blower on the 5.0, build the motor of the 5.0 like the terminator... bla bla. Kind of sounds like ricer talk. Terminator owners could say, well give me coil overs, give me a larger engine..... Can go both ways. 2 different cars with 2 different packages to make power and handle.
great post hit the nail on the head.