Yes, the video quality is deceiving here, makes the engine sound like a gattling gun. Unfortunately, it is kind of hard to tell. You mention that the engine will still die out if you pump the fuel bulb continuously at high speeds, correct? If so, does not seem like a fuel supply problem. I saw the engine die out, but you slowed the throttle at the same time, so I couldn’t tell if it surged then died, or just died right out. I did notice a couple of things though. I saw you holding the key switch in your hand, keep in mind that there are two terminals that are easily shorted out even by just laying in a wet boat, especially in salt water, the "M" terminals. Once these terminals are shorted, the ignition will cut out, which is what happens when you turn the key to "off". I don’t know what is going on with your spark plug wires/boots, but I saw what looked like tape where the spark plug boot/covers should be. You can eliminate boat wiring problems easily by disconnecting the two primary stop leads that come out from under the mag plate. Simply find the two black plastic snap connectors and disconnect them. Please know that you won’t be able to shut the engine off with the key switch when you do this, so you must be very careful while driving/filming, you will have to shut the engine off by choking it out (flooding it). Run the engine at WOT with the primary leads disconnected to see if the problem disappears, boat wiring will have to be examined if this solves the problem.
I know the engine sounds kinda rich at high speeds, but I really think this is just an audio problem/deception, you would know best, does the engine really sound like that at high speeds? I think you have eliminated fuel delivery questions by pumping the fuel bulb while the engine is running at WOT. But, that high speed jet may be getting intermittently plugged with debris at WOT, which would cause the engine to surge/stall. The hole in that jet is fairly large, larger than you would expect. Did you actually remove that jet when you cleaned the carb? If so, what tool did you use to remove/install it? Using a regular screwdriver can bung up the threads, jam/damage the jet, and introduce metal debris into the carb. The jet must be completely seated into that bowl also, there will be a fuel restriction if the jet backs out some. I would tilt the engine up slightly, then place a clean container under the bowl drain plug and remove it, might be a good idea to disconnect the battery to avoid sparks also. Next, using the OMC jet screwdriver, I would check the high speed jet to make sure it is seated/snug in the bowl. If it is, I would go ahead and remove the jet, letting residual fuel drain into the clean container you have put under the bowl drain. Once the jet is out, I would go ahead and pump the fuel bulb a few times and watch the fuel as it drains into your container, look for debris. Have a look through the jet to see if debris is caught in it, go ahead and run a soft pipe cleaner through after inspecting for debris. There might be debris in under the inlet needle seat as well cutting off fuel flow intermittently. Again, I will mention that water in the fuel could be a factor as well. Remove the filter bowl and look for water, that mesh filter might be gummed up also.
I’m sorry I can’t be more sure of what is going on here, video quality can oftentimes be deceiving, so I can not say for sure whether the problem is ignition or fuel related.

All of the ’63 models show a 67D high speed orifice. If you were to need a new one so you don’t have to question if it has been tampered with I have them. Just let me know.

Dan in TN