With that kind of power in a 29 it will run too fast to be safe, I would guess mid 80's, what does the owner say it will run for speed,
A friend has an 06, 29 Fever w/ single step, single 525 EFI, it runs 76 top end on gps ,at that speed it is very loose on the water.

He said 90+. But it gets un controllable so he can't get a top speed out of it. Has imco boxes and Mercury racing drives.

Also. They are 540s. Not 509's. He just sent me a picture of the motors

the bottom line is, way more power than that boat can handle...but if you feel you have the balls by all means go for it...just ride alone