You can count the teeth on your gears if you take the drive off or put motor at top dead center on the timing mark, put in forward gear, mark you prop location, rotate the motor with a breaker bar one full rotation, see how far your prop traveled (should be 1 1/2 turns) That's a 1:1.5 gear. That's how they used to tec our boats in APBA Factory classes. Don't forget a 1.65 gear is pretty close.

Might be easier to pull the coil wire or plugs on the coil, put in gear, then jump the slave solenoid. Crank it over several times counting the prop and the crank

Edit: make sure to feed the drive water when doing this, no reason to take a chance

Couldn't you just take the drive off and rotate the drive shafts one turn

Yes but rotating the engine only takes about 5 minutes at best with a friend.

My only concern would be bumping it exactly one rotation. A 1.65 gear could be confused if you were not exact IMO. I'm not a mechanic just someone who has been through Tec many times in APBA LOL

Rotate the motor at least 10 times, this will be easy to determine by dividing the crank vs the prop

your Scarab should be around 70mph. I have a 2001 twin small blocks 23 mirage plus, stock it ran 67-68mph at 5100rpm. As TRC2 said, check for spacers, mine had them also, would let the tabs come up to parallel. They are 383's now and best it has run is 74mph. I have 3 sets of props that "I" have had the check to be true and correct. 23 mirage plus, 25 mirage, 26 hydromotive 4blade. the 25mirage have been redone again to mirage plus specs. in next few days I will run all 3 sets and get good numbers of RPM, Speed, Slip.

What’s your top speed I got a 29 with motor with each putting 355 hp I hit 64 bravo drIve 23 mirage

I believe the motor spins 1.5 times for 1 prop revolution if I am not mistaken.