Correct site to ask the question.
I do not know the answer to whether the rear carb would hit the firewall, others may.
Lots of differences of opinions on 2 vs 3 carbs. I personally feel that 2 is a better setup, but more difficult for the novice (no offense intended) to initially adjust on the vehicle. Once adjusted, very reliable if you use reliable carbs.
As to which carb to use, LOTS of threads in the archives on this site concerning this. Do a search, and you can probably find several days reading. I personally would suggest in order Carter W-1 from 1946-1948 Chevrolet, Carter WA-1 from Hudson Twin-H power, Stromberg or Zenith aftermarket carbs. Others may suggest the use of Holley 1904 glass bowl units (really cool looking, but calibration can be difficult) or Rochester type B (personally feel these would be better used as a paperweight if they are clean!)
Another option may be the triple one barrel SIDEDRAFT Corvette unit, but clearance may be an issue. This setup used Carter type YH carbs. Looks great, but very pricey!
Jon.
