Kodak Vericolor Slide and Print films
I don't know if Kodak still manufactures Vericolor Slide Film and Vericolor Print Film. They were C-41 process films which were designed expressly for making colour slides and transparancies from colour negatives. In both cases, you would have had to establish a proper colour balance for each negative printed; like regular colour printing, they usually required yellow and magenta filtration.
Both films required careful attention to dust control, especially when making contact transparencies from large format originals on the Print Film. An advantage was that, with the proper equipment, you could crop and otherwise manipulate the final product, and they could be processed in a regular C-41 line, without any special adjustments..
If these films aren't available, or you don't want to go to the trouble of colour balancing an enlarger or duplicating set up, you could try making (or having made) a print, preferably on glossy or semi-matte paper, and copy it onto slide film. Most camera original films will give too much contrast and saturation for a good reproduction, so the best choice is a film like Kodak's EDupe film. Again, as it is a laboratory film, it will have to be colour balanced, and is designed for tungsten illumination, although you can filter it for daylight or electronic flash. For tungsten illumination it usually requires yellow and cyan filtration.
If EDupe is unavailable, or hard to find, a good, neutral film like Kodak EPN (is it still made?) could be used, although you may want to opt for a slight increase in exposure, coupled with pull (or drop) processing, to bring the contrast down a bit. A half- to full-f/stop usually works out well.