408 stroker header size

TTI headers fit around an 8 qt. Milodon pan which is a touch shallower than the Moroso for ground clearance. Only glitch is that it needs a notch cut out of the frame rail lip for the right front corner of the pan to clear during engine installation/removal. They also have a 7 qt. which costs more but fits better.
A mini-starter would fit well and you can use a 3.5" filter without an adapter. A 3" exhaust won't restrict the flow. My Dart ran a bit faster with X pipe & Dynomax straight through mufflers over open headers. (May require some carb tuning for best results.) I still like to be on the conservative side with headers, especially with a dual purpose car. I had a W-2 360 in a 2,850 lb Challenger race car (10.22 best) and considered 1 7/8" as plenty. Bigger would be better with nitrous, but how often do you use it? Just like how often do you max out the engine which might benefit from the bigger headers. I'll relent and say 1 7/8" may not hurt street manners much, especially with more mods later. But I'm just going by what has worked for me.