Im putting an LS1 with a 4sp auto in my 57. It will be fuel injected have plenty of horsepower and still knock down 24 mpg. I wanted to try new tech in an older vehicle after running carbs for so long. Of course my truck was already modified and didnt have the original engine. But down the road if I get something with a six in it I may decide to build it for somthing different and cool. But I still say you can get more bang for your buck in a V-8.