Headers

Hi
A few years ago a picked up a set of headers from a guy moving out of state.
he said they fit a 318, and that all I know, there are no marking on the headers
if they do fit my 74 dart with 318, what would you suggest for a good sounding
muffler, something not loud but had that nice rumble to it?
and should I run the pipes out the back of the car, behind the rear wheels
in front of the rear wheels? If I do install these I want to do the whole
setup in one day...
Best