You say the '56 engine has 12V starter and flywheel. If it came from a truck it should have the foot operated switch.

If it has electric solenoid it came from a car. You can buy a unversal key switch with start position or you can use your stock switch with an added start button.

If you want to keep it foot switched find a '55-'59 truck starter.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.