Based on research and what I have on my 67 383 4 speed, 2780915 heads were also used but had the smaller 1.60" exhaust valves. And the 4299 carbs were used on 4 speeds sold in Canada.
All 67 383 A-Body's came with 516 heads, basically the same bowl as a 915 but with smaller valves, if your car has 915's then they have the larger valves. BTW, there were 457 Dart GTS's made, don't know where the 458 number came from?!?