tti headers

I agree with Rocket that TTI's 1 5/8"-1 3/4" step header will be much better for your application. They work well in a pretty wide range of power levels. I have them on my Dart Sport running mid-low 11's weighing 3,540+ lbs. I never had it on a dyno, but I'm sure it's well over 400 HP. 360, 750 carb, LA-X heads (unported w/original sized valves), 10.5 compression, 904 trans & footbraking.

The fit in my car was excellent. Room to remove & install a mini-starter, no oil filter adapeter, plenty of ground clearance & no dings. One can move things around a bit by shimming engine and/or trans mounts if necessary. One just has to remember that 40+ year old cars can vary in production quality especially after that many years of abuse, possible accidents and replacement of suspension parts, mounts, etc. that can vary a bit also!

I've never messed with a 4-speed so I'm not familiar with any fitment issues that may arise there with any headers. But even with that, performance-wise, it's always better to select a size a little on the conservative side than a little too big!