Re: lower unit water intake

The rubber seal is simply a correctly sized O-Ring. If you don't need to take that lower unit apart and if it is not leaking, don't take it apart.
Take a plate of thin aluminum and drill multiple 1/8 inch holes in it then epoxy it over the intake. Sand the paint off the lower and sand the plate where the epoxy will be.
Really though, unless you are boating in weed clogged or chunky water the screen is not necessary, neither are the fins.