Header design and fit questions open up a whole can of worms. Unless you're running some sort of custom exhaust system with equal-length header tubes from each cylinder tuned for a specific power gain at an RPM range most street engines never see, headers of any kind just make a fashion statement when the hood is open. They also increase the under-hood temperature and noise level, and roast spark plug wires. Pick whatever looks good to you, and put up with the problems they create. I believe I could outrun anyone who wanted to GIVE me a set of headers for street use. Cast iron exhaust manifolds with the outlet near the firewall on both sides make the most sense for pre-1955 trucks that originally came equipped with a stovebolt six, and until very high RPM ranges are encountered, there won't be a measurable difference in power on a dyno run.
Jerry
