Good morning, Jason~
I know this is after-the-fact, But I thought I'd share - for you and others - a few of the ways I've handled flapper-board chocks on South Bay Duckboats.
Here is one where I retained the factory chocks - but made new flapboards and added a middle chock so the boards will lay level when down. This makes them useful for setting decoys when setting out or picking up stool.
The cleat on the middle chock can be used for securing the boat to a "bog stake" when gunning - or lashing the boards down and securing the cockpit hatch when in transit or storage.
Here are some new chocks that use the original dimensions and mounting holes.
Here is a new set with beveled mounting surfaces - so that the tops are level with the water. I use the beveled cut-offs below decks as backer boards so everything makes up square and tight with the carriage bolts.
I used a level to measure the bevel angle.
It is critical, too, that the chocks line up so that the flap-board hinges are in alignment with each other (and so do not bind when used).
The chocks are bedded in 3M 5200 - but 5400 would suffice.
BTW: A handy feature is to have removable hinge pins - so the the flap-boards can be stored inside the vessel off-season. I fashioned these out of 1/8-inch brass rod - with decoy line "keepers" so they do not get lost or fall overboard.
All the best,
SJS