2 Speed Wiper Switch Question for 1973 Duster

The only way I would know to approach an aftermarket setup (and I'm not smart enough) would be to design an electronic circuit to mimic the OEM switch. I hate dealing with Mopar wiper setups. They are not well documented and I don't have enough parts (from various cars) to sit down and dissect them, plus they are way to valuable to do so

Find an OEM switch, pay the price, and be happy. Either that or CAREFULLY take yours apart and try to repair it