HP & TQ on a barvo one 1" shorty and still have longgivety , looking @ About 600 / 645 or so.

All depends on how you drive it and what condition it is in. If it has a lot of hours and is loose, or you drive it without respect, it can and will break.
Friend of mine is running an old style B1 (97) and his 28' Checkmate runs over 90mph. Estimated power is around 800hp. I have gone through it once, after 7 yrs and he has another 5yrs on it since then.
He knows how to drive it to live...

Hope this helps.
Dick

FOR INPUT more then likely drive it with respect in 1 to 3' ers 50s to 70s mph

Also consider the weight of the boat, (you don't mention your weight) it's easier to live with light torque load regardless of speed to a point. Heavy load is the bane of Bravo drives, that and wave hopping. LoL Like I always say though, it was never rated for more than 600HP. I thought they should have stopped at 500HP. The 500EFI with Bravo XR/XZ was a good solid combination. Like he said though, you need to know how to make it live but I'd rather have something sturdier at that performance level.

is about 5600# it's the same as my advitar, 2000- 271 Formula

It does not matter how fast u go even in 6 footers,,its how u throttle it !!!