Footstrap purchase and attachment methods

Can anyone tell me how to purchase online footstrap lengths or who in Byron gold coast area to go to? I want to renew my straps on my old Hayden wave ski 1976 model they are attached by ss screws , no real problem but also want to replace broken straps on my grandsons nipper bennet fiberglass board . These appear to have been originally riveted on and stub of rivet is sticking out of deck . What is best way to reattach these for a non professional ?