I’d start by double-checking the raw water pump and impeller since that’s often the culprit with high temps. Next I’d look at flow restrictions in the manifolds/risers, then verify timing once you get a working light. If all that checks out, I’d inspect hoses and the circulation pump for hidden...
To my ear it does sound a bit metallic, almost like piston slap or something rattling loose. I’d keep an eye on it and maybe do a quick compression check just to be safe.
Tutuapp
I’d definitely start with that compression test to rule out the basics, then check if the carbs are actually delivering fuel into the cylinders. A quick spray of premix in the intake can help narrow it down fast.