Trunk mounted battery

CD relay borg warner S605. I believe the Napa ST-85 may be the same, verify the st-85 is a continuous duty.

Starter relay, any ford starter relay from a 65-73 car should work. Pick a model and go. Jeep just look around on rock auto for a picture of a relay that looks similar to the ford unit, mid 80's will be close.

I like the relays that don't need a ground wire, internally grounded units. Less clutter.

There are drawbacks to EVERY master cut off solution. You have to pick which potential deficiency you can live with if the system fails. There are some that if a single component fails in a closed position, the car won't stop when the master is turned off. Others, it doesn't matter if the relays lock open or closed, the car dies.