For 25 or 6 to 4, I'm pretty sure Kath used a Cry Baby Wah and a Bogen Challenger PA head plugged into a Fender Dual Showman. You could probably sub out the dual showman with a twin model and use a cab or IR with 15" speakers. For the Bogen PA, maybe try the studio tube pre, or another preamp, directly into the twin model.
https://line6.com/data/6/0a020a3d59d359150930cbdec/application/pdf