I had the pleasure of taking this 46 Skater Supreme out last August with 2x725hp Seateks and it ran a strong 100+ with overpitched props on it.
Its well documented on here running 106+mph

Not sure about the limitations of the Trimax drives, you really should go with Arnesons as they are trimable.
This boat had ZF301s with a ratio of 0.86-1

What you like on engine room length? this boat it was impossible to change the raw water impellor without pulling the motor!

Thats the one! I have talked a little with his son and they are selling the engines and drives to put 4 mercury 400's on it.
I am far from an expert but someone told me that there is no need to have trimable surface drives since they are already cutting the surface. The trimax drives we are using are the ones made by Fabio Buzzi and they are adjustable up and down to find the best handling and top speed.
These are the engines, gearboxes and drives. https://www.dropbox.com/s/mj50mq9bvw...11%29.JPG?dl=0 the gearboxes are drop box ZF IRM301 and the lowest ratio for them are 1:1 but they are no longer making spare parts for them so we need to find others for next summer.

Your spot on, the parts are now obsolete for these boxes.

I am using Arneson Drop boxes and 800+ motors in mine.

Ouch.. this is what the engine room measures in millimeters. 2010mm total length and the engine and gearbox total length is 1755mm. https://www.dropbox.com/s/naakwftvtm...orrum.jpg?dl=0

Just PM you.

What have you done to get 800+ out of them? I have talked some to a guy at Seatek and he told me that the only way to get more out of them was to change the turbos and injector nozzles. I wanted to turn the fuel pressure up but he warned me that the engines would overheat with extra diesel because the turbos were already maxed out to get 660hp.

Yep that's what I got, you might want to check your transom angle, that's a fixed shaft and you will need to accommodate a u joint to get the engine parallel to the bottom is the transom is the standard 12-13 degrees.