It would follow that it might need around 10 1/2 minutes (8 minutes times ~1.33) in RLC 1+4. That's at box speed, which is supposed to be 80 in daylight, 40 in tungsten---I don't know what your lighting was, but you might fiddle that time to compensate one way or the other since you exposed at a speed somewhere between the two.
Yeah, don't waste your ortho film on testing it---it blocks wavelengths that the ortho film can't see, so it should have no effect to speak of. But it should give you an orthochromatic-looking image on pan film.
Thanks for your help, I used studio flashes, so the speed should have been 80 instead of 50, shall I try 9 minutes?
By any chance do you know what would be a good filter to make the ortho film look like early blue sensitive only emulsions?