Finally back to working on my 63 dart

The only tubular header that works for a "street" driver 170 is the Clifford. You need to modify the front 3 tubes, so the collector sits higher above the steering box, if you have manual steering. With power steering I don't think you can get it to fit without major reworking.
Aussie speed has a nice header that fits the 170 engine, but the tubes hang very low, and will have issues with speed bumps, driveways, etc.

If you don't have much money to spend, and you're not racing, I recommend just getting a good stock exhaust manifold and using a low restriction 2 1/4 or 2 1/2 single exhaust to the back of the car.
Any type of new header with pipes will cost in the neighborhood of $1,000