I agree with
@Paul Howell -- from what I've seen on YouTube, remjet removal isn't difficult. Two steps: a process temperature sodium carbonate bath with very vigorous agitation and a thorough fill-agitate-dump-repeat until clear wash before any development, then rub the residue off the base side with wet fingers after fix (may help to put the film into another sodium carbonate bath, as it does loosen the binder that holds the remjet in place.
The first carbonate bath and wash removes what's loose emough to otherwise come off in the developer and hence float around, land on the emulsion, and cause un(der)developed spots; the second gets rid of the rest.
You may also want/need to give the film a light bleaching with Farmer's Reducer to cut down the density of the filter layer. Otherwise, that layer can make color films so dark you'll have trouble seeing the negative silver image.
Another option that does work fairly well with Kodachrome is B&W positive -- in this case, you'd perform the second remjet removal after first developer and stop bath, then bleach away the developed silver (many threads on Photrio about this process) in the light, followed by redeveloping the (now fogged) remaining halide to produce a positive image. This removes the filter layer as well, and has the potential to produce decent B&W slides.