I've been running an F4B for 20 years. Even Shelby admitted to Edelbrock that his manifold was better than the SFM manifold... These (the F4B) average about $250 on Ebay... I use a Holley 1850-12, 600 CFM carb, vacuum sec., manual choke. I NEVER use the choke. I get 22 MPG as long as I'm not a 17 year old...
I did get one of the 465 CFM carbies from Holley... This was configured as a manual choke (cable).. But the biggest problem I had was, it was not set up for vacuum advance.... It was for a client's car. In the end, I reconfigured the carb with a different base plate so I could have a vacuum advance port and at the same time I set it up so it could be a "hot air" choke, instead of an electric choke, or manual choke. It ran, but was not what I would call "ideal"
In the end I opted for a 1850-12 (vac secondaries, cable choke) but modified it for the "hot air choke" as the car was a Mk1A but had a 5 bolt 289... The car ran great. I couldn't make it run for "shit" with the 465 cfm unit.
You have to remember... the leaner the mixture, the hotter the car is going to run....
Heat is the enemy!