TTi step vs. 340 manifolds

I have a race car project already and this car is numbers matching so keeping it street smart. New paint, very good interior, fold down seat option. Very clean.
My goal has been to only do Day 2 mods aside from an MSD distributor and an under dash MSD 6AL, hence the LD340 and not an Air Gap. I was just planning on the intake and header upgrade. Even the stereo is going to stay AM but with a Bluetooth conversion. Really wanting it to look original. I would make an exception on the TTi’s and the period correct LD340.
The LD340 and TTIs together could add 30-40 HP. That right there should answer it. I agree with @abodyjoe that if we were talking about a lesser quality header, leave them on the shelf. We're talking about really good headers. Use um.