Tips for V8 purchase sought

Hello, after many years of thinking, I have come to the conclusion that it is no longer possible without Ami-V8! Would like to buy a car until about 1970. (However, preferably 50s) Since I want to meet with the car as often as possible and not only 2 times a year, I have to address an unloved topic: consumption. I know that such a car is not a savings miracle, but there are certainly also differences between GM, Ford or Chrysler engines, between new engines. the larger engines (e.g. 350er) and the relatively small V8 in 50s cars. Or with single or multiple carburetors, 2- or 3-speed automatic. Could I also imagine that a manual transmission reduces the consumption strongly (although I would prefer automatics) , has someone experienced there? Have heard more often that Mustangs should be relatively economical with the 289er (approx. 12-13 liter/100km), can this be? In which area does a Chevrolet 350/350 combination move in a car ? (Is probably on the As I said, the car should then be suitable for everyday use, and there unfortunately the fuel costs play a big role today thanks and greeting! P.S. Was something unpleasant to me to ask here, because now it probably means to drive V8 again and save etc. But if I buy a car here because of a few tips, which needs 5 liters less than another, which I like just as well, then it has already been worth it!