Rear Coil Spring Insulator Installation
 

Perhaps a silly question but when installing new coil spring insulators on the rear springs, should I glue and/or zip strip them to stay on?

No, they should stay in place by themselves and then the weight of the car will insure they stay put.

I ran into the same problem when I installed new springs in my 65. The new insulators would not conform to the shape of the spring. I had to zip tie them on to keep them in place long enough to install the springs. As Rich said, once installed the weight of the car will hold them in place.