Chainplate fabrication

[county]

Im fabricating new chainplates and will be using 1/2" bolts. My question is should I over boar the holes on the chain plate by 1/32 or 1/16 or some other fraction of an inch. My concern is that if I make the holes 1/2" when I bend the chainplate to the shape of the hull the hole will be slightly smaller not allowing the 1/2" bolt to pass thru.
The chainplates will be external on the outside of the hull.

Any thoughts would be appreciated.
Thanks.