Interesting. The throttle lever on my ‘82 H30 appears to be cast aluminum. Is was originally coated with a thick layer of red plastic material, half of which had already peeled off when I acquired the boat in 2006. I took it to my auto mechanic shop and asked them to grind or wire brush the remaining plastic off. It looks fine and I haven’t broken it yet.
The set screw used to work loose occasionally until I put some Locktite on it.