I am only a backyarder but have done same as you plan to do only the once repairing an old 80 s 6 foot twin fin - looked great but for me mine came out too heavy . Since then I have only repaired and glassed as needed - rebuilt about 10 doing using method . have had 2 boards done by professional board repairers - one being my old 70 s single fin - both had the fibreglass stripped and replaced .
great thing with old boards if you aren't happy with the job - sand back and go again
enjoy