If Free Dollars was the price just rebuild what you have. I though that was the #1 rule of street rods. Use what you can out od what is given to you and scavange for the rest.
Honestly I think you should be able to flow the cast irons ok and through on a nice Edlebrock 1901 carb. You can get those remanned as well. If you need exhaust hook ups, Hedman makes an nice, but inexpensive hedder.