Is it really a 1998 as your handle would imply?
If so, I'm thinking that want to seal and extend the vent on the the distributor.
I would apply dielectric grease to all spark boots at the coil, distributor, and plug.
Then I suspect that you want to get rid of your mechanical fan so you don't throw a belt while you are underwater.
You will probably want to disconnect, Dielectric grease all electrical connectors and put them back together.
Then, if you are real serious about this whole submarine experience, you will probably want to extend your exhaust above the water line.