Keep in mind these KB motors are rather amphungry, so a 'cheap' 6S Lipo is out of the question.
Also watercooling is a must, not a tiny aluminum coil around the can, but a fullsize coolingjacket, covering the entire can.

These can be bought, or home made, I have a 'tutorial' and some pics, showing how I go about it.

I wouldn't go for metal props as yet, find the right size and pitch by trying some Graupner K-series twobladed props, I know, these are officially surface piercing props, but I've been getting good results with them, as they are much stiffer than the plastic ones.
Start with something in the 37,5K, 40,5K size and work your way up, keeping a close eye on the components temperatures.

J.M. has a valid point in the surfacepiercing suggestion; as the hull is stepped, it will draw air under the boat.
As the suggested powerplant will allow the boat to run a lot faster than stock, the aircushion under the hull may become a problem when it reaches the prop and rudder.

If you use an K-series prop, the propulsion may not even suffer a lot, unless there's a massive amount of air drawn underneath, but the steering will.

Some time ago, I've been running a 30" stepped hull as a motor testbed, with a subsurface prop (Ø 40mm). On 12 cells and a 700 motor the speed was quite ludicrous, and the steps worked fine and left my rudder standing in a pocket of foam, behind the prop. My input from the transmitter was ignored completely as the boat raced towards a brick wall..., only a substantual reduction in speed, dropping the hull off the plane, gave me back steering control, just in time to avoid a collision.
Quite a heartstopping experience...

I expect your 'rather distinctive' step will have the same effect, so beware. (My testhull was polyester, quite solid, your ABS hull will disintegrate on impact...)

Making it a surface piercing drive would avoid such steering issues. (but would require another KV, aim for 30.000 rpm for such a drive)
This one would actually suit: Keda KB45-11L 1649kV 70A Brushless Inrunner, at 85% efficiency on 6S would be around 30.000 at the prop.

Regards, Jan.