however I feel it would look much better as a B&W converted image.
There is no ethical issue if you indicate to the viewer what you are doing. For example "Digitally Altered Scan of Kodachrome 35mm Slide." APUG is not the site for presentation of "Digitally Altered" images.
However, If you want to contact print the slides onto Wet Plate and scan those B&W images to post here, that is great.