Worth the effort to maintain the laminate skins especially on high load fittings like jib/genoa tracks on cored decks. Keeping the skin intact and ‘backfilling’ the hole is less likely to fail and allow water intrusion. Straight ‘over drilling’ is easier, but less strong, harder to ‘center’the fasteners inside the epoxy plug without drilling a larger hole to ensure the plug completely surrounds the fastener, and is more likely (under worst case) to pull the plug as it is not encapsulated by the skins. The last thing you want is the plug to become compromised! If the hole is damaged, try to maintain the inner skin at minimum. A bit more work, but I have not had one fail yet and the core and fasteners are positively isolated. I am doing this right now- hence the note. Check ‘West System’ how to for additional info -this popped up first on google. Don’t forget to seal hole prior to plugging with ‘neat epoxy coat’, then thickened ‘pooky’. Let’s keep those holes in the deck sealed, strong and minimum size! I use ‘bent nail’, Allen wrench, and dremel bits depending on wet or dry core. Hope this helps - GO M-15 #330 ‘Cahoots’ https://marinehowto.com/sealing-deck-penetrations-to-prevent-core-rot/