Are you sure the T350 was ever installed with a Model B carb engine? All the ones I have ever seen use throttle cables, not throttle rods. They also use a bell crank to operate both cables.
I believe you are searching for a part that never was.
The T350 came into production in 1969, before that, the power glide was used. The Mono-jet was replacing the Model B about the same time ('68 on up). You need to look at 1969 to 1974 or '75 GM (Pontiac, Olds, & Buick) a-body, Vegas, and trucks, as they all used the inline 6 with T350 transmissions. Even if you find the brackets, you will need the linkage, intake, and carb to use it.
Joe
