I had Offy dual carb intake on my 54 when it had three speed on the column and had no claearnce problems. However, the only exhaust that has been on the truck was a Corvette split manifold and later, a set of Clifford long tube headers.
[IMG]http://thumb17.webshots.net/t/69/69/0/22/89/2922022890047579877PysoHd_th.jpg[/IMG]
I also had to remove the driver's side firewall to fender brace.