If the car is in good shape, it will handle just fine. There are no long grades (it's a coastal highway).
The single biggest concern is emergency braking (read, idiots who pull out without looking, and those that slam on the brakes because they *might* miss a view).
So take a flash light with you, and do the following:
1). Check the brake reservoir level, should be full of clear fluid.
2). With the engine off, pump the brakes 4 times on a two second count ("one-onethousand, two-onethousand" pedal down; "one-onethousand, two-onethousand pedal up). Then hold the pedal down with a medium hard push (about 40lbs to 60 lbs) for about 30 seconds. Make sure the pedal does not start to drift towards the floor. This will show a leaking wheel cylinder or bypassing master cylinder.
3). After the above test, take your flash light, and look at the bottom of each backing plate to make sure it is still clean and dry. If there is any moisture, stop! Take the car for a brake inspection.
There is no back up system on a '65-'66, and the P brake is very poor in an emergency situation. So the brake system needs to be in
exceptional condition. Any good tire and brake shop can do an inspection in less than a couple of hours time. A great opportunity, to grab a killer lunch, at one of many excellent restaraunts, and maybe stroll around for a bit before the long drive home.
If the brakes are good, take your time, and enjoy the ride. I'll bet the car has been down this road more than a time or two.
Good luck!
And yes, a follow up to this thread with pictures of your trip is mandatory!
Welcome to the wonderful world of Classic Mustangs.