I agree on safety first always, have a tow boat and leave the deadman throttle to kill the engine when released that’s how it was designed. Never go out unless there is a tow boat there. Agree on rope lashing the engine  from the transom left to right around the tower. On the steering as noted above ditch the springs you want positive control. Also the steering tie backs attached to the side coaming should be rotated 90 degrees from where you secured them (less chance to pull out) and the cable needs a steel thimble eye to prevent cable from a sharp crease. Are they bolted thru with flat washers (need to be) can’t see if that is the case? For further steering safety use 2 cable locks on each side not just one.

Adjust engine height higher and trim angle as you gain real on the water experience going straight and turning. Start with engine deep and prop shaft level with the rear bottom surface. Eventual great height is center of rear of prop shaft about at the bottom, pending on boat and driver. These boats can send you into low earth orbit in a heart beat. On the Glen I Super Spartan for real performance in the future add correct designed air traps to better control the under hull air compression and air release at the sides and rear. For real performance you want the sponsons off the water about 1-2″ for less drag (see my avatar). If under way at straight speed with you in the rear if sponsons are dragging the water you need to check and adjust engine prop shaft angle to bottom, you don’t want to kick out the engine to gain sponsons off water, hull aero dynamics and air traps will do that if designed right. On my hydro (avatar) took me many hours of testing and modifying the air traps to get the boat to fly like in the pic. That hydro runs in the mid 60mph range with the Merc 25ss set up for heat racing and was very competitive.

Are you using an adjustable turn fin on the left sponson back or on the boat bottom with left offset or in the centerline of the hull? Better off with the left sponson rear fin but only for left turns. If on bottom (not best) should have left offset so not to spoil water/air mix flow to prop.

Do you know the specs on that prop like diameter and average pitch?

Nice work on the Spartan, have safe fun

From a former APBA Region 5 hydro racer in class 20ssh and 25ssh.

Use other means as a chick magnet not this race boat 😉

I agree with Tubs. Everyone seems to be looking for a free ride at your cost!