(Ilford Ortho Plus in Rollei RLC)
Rollei Ortho 25 at box speed in Rollei RLC 1+4: 8 minutes...
...so let's try to compare the responses in different developers of Rollei Ortho 25 and Ilford Ortho Plus. There's not much in common to go on, unfortunately, due to the limited range of films with times given for RLC.
Rollei in D-76 stock: 6 minutes
Ortho Plus in D-76 stock: 8 minutes
So that suggests, very very very loosely, that Ortho Plus is about 33% "less responsive" than the Rollei film. 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.
I don't know if that multiple extrapolation ends up being much better than a blind guess, but at least it's something.
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.I just got a bargain minus red filter on ebay and I'll try it as soon as it arrives to see how it works with ortho film, but, from what I've been told, I may as well have bought normal panchromatic film to test with that filter as the effect would be the same.