The boat should have some type of transmission in it. Prolly a velvet drive. You should be able to drive it like a car.
The boat has no ride (trim) control at all. And from looking at the hardware under it I would think that 90mph and the chance that it ever had a big KB in it are pretty slim. With a steep prop strut angle and no cav plates that thing will be a wild ride (not in the fun way) if you try to make it really fast.
Still a cool boat though!
Question: What is that round tube on the transom and what looks like a tiller sticking through on the inside?