When I install the 350 in my 51, I plan on finding an electrical stomp starter switch (old tractors used them) and fabricate a boot with the original stomp metal circle so it will look like the original stomp starter.
I saw photos online of a truck that had this conversion. To start the truck, he had to do the following.
1) Turn the key on (just like the old days)
2) Flip a hidden toggle switch under the dash (this made the stomp starter "hot"
3) Stomp the starter switch
4) When the truck is running, flip the toggle switch under the dash to cut power to the stomp switch
Since he was using a GM starter where the battery cable goes directly to the starter, the stomp switch was wired in like the start position on a later model with a key switch start. The hidden toggle switch under the dash was a safety to prevent crashing the starter gear into the flywheel if a passenger accidently bumped the stomp switch while the motor was running.
