If your engine is not installed, it’s very easy to get the little captive nuts out, and retap them to a standard US thread.
Then you can use regular screws. I also use the little black faucet washers on the outside between the outer bulkhead plate and screw head, to give me more “buffering”.
Maybe it’s useful or not.
The metric screws are probably relatively easy to source, as well.
Rocky
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