Konica Centuria Super, even the 3200 speed stuff had no correction out to 10 seconds.. all gone now.. except the lot of 100 speed stuff in 120 I have.
Anyway, just overexpose the C-41, reciprocity failure increases contrast and drops shadows, overexposing will drop contrast and lift shadows, which you cant do on E-6 or you'd get too thin in highlights and mid tones.
Whatchu talking 'bout? E-6 chems is cheap!
Filtering C-41 with 85A in colder light temperatures I've found from limited testing improves saturation when corrected to the same colour balance. I would suggest some kind of filtration would be very handy at night.