Header Size Recommendation

I ran Stock Eliminator in the 90's, and yes, the tubes were getting bigger then. Our 440 6 pack had 1 7/8 tubes because we got them super cheap, but other 440's had 2" on them.
Step headers were just coming around. They were a lot of money and my partner and I didn't know any one that picked up from them. Maybe other changes were needed to see an improvement.
My Duster's going to be a garage queen that sees limited street use and the occasional trip to the track. I'm just having a hard time getting my head wrapped around the idea that 1 7/8 aren't too big! Of course the mantra over the years is not to go too big. I'm thinking that it would have to rev higher to benefit from them? Stockers rev higher than my street 360, for sure. Plus they use 5-6 K convertors.
I definitely appreciate your views, yellow rose. You're making me think! (ouch) I'll probably start with the 1 3/4.
My plan was to build a 408 and use a 4 spd. However, my money tree has not been growing fast enough. I was thinking 1 7/8 for a 408. Maybe 2" for it?