How can you get 55 mph out of a 1955 pickup with a Chevy 235?

There used to be a company called Clifford Research, that made parts for 6 cylinder inline motors, only. They can help with the 235. I will tell you this, too. The 235 in that year, put out a bit more HP, as an automatic, version, over the stick shift model. You may want to modify the suspension, as well. Art Morrison, in Washington state, has a specialty line for your rig, as well.