Just Another Random Question

Right up until the point it blows up....lol. The real answer is: It depends. It depends on how those miles were accumulated, it depends on how the engine was taken care of...ect, ect. ect.
 
I have personally done heads, cam, intake on a 200k mile stock engine and drove the hell out of it. I sold the car a while ago but it's still going strong. I don't think I would wind it up past 6k but I wouldn't baby it either.
 
To get down to reality, these engines don't do anything past 5k stock anyway, I've winged mine past 6k several times only because I just let the tire spin get away from me, most times I hit second gear about 4-4200, same with third, I run cheap tires on the rear, I just wanna have some fun and impress the grandkids, they think my car is a rocket ship.
 
Keep it under 5K RPM and you should be good.

Back in the day I had buddies that would find out they had no oil in the car, add it, and then put another 50K miles on their 5.0's. Honestly, these are one motor that you really can't kill if you wanted to. Most of the 5.0 death's I've seen are from adding copious amounts of HP.

But, 250-300HP stock 5.0? Keep oil in it and it should last longer than the body.
 
Push it as hard as you want. Mine has almost 178k on the short block, and I still shift it at 5200-5400 rpm. I have a GT-40 intake, GT-40p heads with stock cam and 1.7 rocker arms. If the intake and heads are stock, revving it higher than 5k is unnecessary. Mike is right, these engines will last a really long time if cared for and not being constantly over-revved (or boosted or sprayed).