For electrics -

I like to carry some wire, a crimp tool, connectors, and a small multimeter. Get some one to two adaptors so you can take power off your main terminal strip. For example - I had to run power directly to my stop light switch when I had a bad connection.

Your car does not have many (any?) ground wires.

I like to be able to run power directly to an item, or run a ground to an item as well. To fuse the power wire, you cam carry spade type fuses - take a wire, cut it in a handy place, install female spade connectors on the cut ends and add a spade fuse.

A set of spare bulbs and spare fuses is a good idea.

The condenser in the ignition system is a failure item - if the car won't spark, test the condenser by disconnecting it - if it starts, install a new condenser. The condenser is essentially an open circuit that protects the points from power surges. Carry a spare and points as well.

I have a battery post switch in my car and I always use it. It is an inexpensive one that you can remove the screw connection and put it in your pocket. I have used it for 10 years without problem. Also, being able to disconnect your battery quickly can be a valuable asset in an old car.