The (former) professional in me would always advise changing the gasket...... however, if it were mine I would try an additive first but would council you use
K-Seal as it’s the best there is on the market.
And I know of at least one race preparation shop that use it in every vehicle they prepare as part of their process!
BR
Colin (people often don’t believe me but I know for a fact that at one time (late 70’s) a Jaguar Service Bulletin advised its U.K. dealers to use a slug of Barr’s Leak in every major service on the V12 cars)
