Unfortunately those are the biggest available- I have a set of the 1 7/8" x 3" headers waiting to go on the car, along with a full 3" exhaust and Hooker Aerochambers. I know they're on the small side for any stroker big block. The header adapters TTI included are also not great for airflow, they have some weird bends.

I can't fab headers myself but I am planning on cutting the collectors short before they neck down to 3", and then running 3.5" from the collectors to manual cutouts, and then 3" back from the cutouts to the rest of the exhaust. Can tell in this pic that the header adapters take 2 tight 90* bends on each side to get to the relief cutouts in the subframe.

Definitely brings up a good point that the TF270's are already on the small side and will peak at something like 5500 rpm on a 572, and then it's going to be choked a little further with 1 7/8" primaries. Think that's further indication it's best to keep it at 540-ish for displacement, that should move the powerband back up some.