As for my friends 1980 OTCA, I am now remembering that the serial numbers were not fully readable. I am not sure if the previous owner told him it was 1980 or if there are enough numbers present to determine the year built. The decks on it are not the classic OTCA style but just the standard OT type. (I believe I've seen the same on other late built OTCA canoes). It may very well be that the outer gunnels had been replaced and the person doing that work chose to put the screws from the inside out. (Those outer gunnels are not extra wide either).
In the end you gave me the simple answer I was expecting, outside in. The two OTCAs I referred to were red herrings that clouded my deductions. All is good, sort of, in the world. Thanks as usual for doing what you do.