"relatively fast"? like compared to walking, or an electric car, or a stock AD?
"stock" rear can be 3.73 or 4.11 - the optional 3.07 would be the best bet for highway speed, which depends on gearing, not horsepower - the 4 speed won't help anything except low end grunt work, tho' it'd be best w/ the 3.07 rear
the 283 responds well to use of a 4barrel, if you've got a 2bbl now, but fancy headers and exhaust are just noise & eye candy for it, not horsepower [which again, doesn't mean better highway speed anyway]
Bill
