I beg to differ on the 283 V8 engine not being available on the 1957 model trucks.
The 283 was an "unlisted" option in pickup models, and the 283 V8 was available in 1957 on ALL models, cars and trucks.
The way things were run in 1957, I wouldn't doubt that if a person had the right contacts within Chevrolet, he could have had a fuel injection in a truck if he wanted it bad enough.
