Look up the transmission graphs for the gels you want on the Kodak side, then compare them to the technical curves for the Rosco stuff.
While not optically perfect, the theatrical gel at about $6 per 20x24 sheet is a lot more affordable to experiment with.
I do have a set of wratten separation filters as you are looking for, but alas in only the 2x2" size.
The other option is if you can get to the insde of the lens, ie if the lens is fitted to a shutter, put the filters inside the lens.
Lock the camera down, swap the lens board out between shots, and screw and unscrew to change filters on the inside of thel ens.
More of a PIA, but likely a lot less $$$ to try this approach. I would only try this for studio still lifes, or copy stand work but that is usally the case for making separation negatives, now isn't it.