I know nothing at all about convertibles(other than my Miata which has a hard top I never take off), but in general there are a couple of different types of basic electrical switches. One has 2 terminals...it does not matter how you install this switch, all it does is break the circuit.....whichever direction you install it in works. The other type is a 3-terminal 3 position switch...it is on1-off-on2. In the on1 position it supplies power to circuit A, in the on2 position it supplies power to circuit B, in the off position it supplies power to neither one. Now, with a 2 direction electric motor(such as an electric fan, or I would ASSUME a convertible top motor) swapping the ground and the power will determine which direction the motor spins.
In the case of a 3 position, 3 terminal switch it still doesn't matter which way you install it from a functionality standpoint, the switch itself doesn't care(worst case scenario is off is up and on is down). it is going to supply power to the top when switched to the top and power to the bottom when switched to the bottom. If I were you though, I would simply hook it up and test it before installing it in the dash...you might have to make some jumper wire extensions, but you should have some jumper wire extensions anyway as a tool for testing things.
There are also 6 terminal 3 position momentary toggle switches, but that is getting into slightly more complicated territory...dont think Ford used those in the 60s.
