Inside the carburetor, where the gas line connects.
Any door from a 1977-79 Caprice/Impala would fit (assuming it's a similar bodystyle)
Doors from a 1977-79 Caprice or Impala would be interchangeable.
Check fuses
According to tirerack.com the original tire size is: 225/70-15
The fuel filter may be clogged.
Electric.
Yes
Either a 305 or 350 V8
Yes
Any other grille from a 1977-79 Caprice/Impala would be a good fit
1977-79 Caprice Coupe were the only years for the squared off rear window.
gas consists mainly of 79% of noble gas