A cosmetic restoration of the cowling will not really improve reliability or engine performance, but it will instill a sense of pride to the boat owner to see their classic Yamaha marine engine looking superb - and boats are all about aesthetics as well as being water dynamic aren't they?
Other lower cowling components you may wish to consider:
Add as many items as you wish to the same shopping cart, new bolts 97D9506016 and washers 9299006600 (to replace those that are corroded beyond use) for example, and still only pay the same single fixed price shipping cost.
Please be aware that this component may have other applications within the Yamaha model range. So ensure the part-numbers you order are correct for your model.