You will also need a Raspberry Pi 19 and a GSM transmit module to impersonate the old-timey cell towers they used to use. You can purchase one for about $3 or so and run this script...
After you have hand built a new battery that fits it, built a LCD shim to connect to whatever the latest standard is, etc.
Older cars are simpler, both in total, as in the requirements to retrofit replacement parts. Your average machine shop/etc will be able to keep that 914 running for the next hundred years. And when they stop selling gas, you can convert it to run on everclear.
step 1. prepare a usb with files needed to jailbreak the car and be able to connect to your wifi
step 2. setup a home network with dns/ntp and a reverse engineered tesla server that will authorize the car to work
step 3 set date to reasonable values that the car will accept
step 4 do some button dances to start the car from the usb
…
ill leave the rest to your imagination