The thing with switch-hitting or stance-shifting, whatever you want to call it, is the feet. Nothing to do with the hands really. It's how you're used to balancing, and that's what needs revamping first before anything else. Can't just stand in front of a heavy bag and punch as a southpaw - look at what your feet do normally, then try to copy that exactly but on the other side.
Sparred a southpaw for the second time today. Though I'm not very experienced, I started a month or two before the other guy. The first time we sparred I didn't realize he was a southpaw til halfway through the 1st round. Wasn't able to do much with my jab or straight right and had no idea what to do against a southpaw. Only thing saving me was I had better defense and footwork than him. In the 2nd round I decided to switch to southpaw just to throw him off. I would land a jab or two and quickly switch back to orthodox as he was backpedalling. Had a lot more success this way than fighting him strictly orthodox. Then I read and heard it's not a good idea to switch stances and to just focus on one, so today I fought just orthodox for the 1st round. He improved a lot since the 1st time we sparred and I wasn't able to hit him much. Landed a decent amount of body shots but he got in more head shots than me. 2nd round I decided to try switching to southpaw again. I was finally able to land some jabs and combos and put him against the ropes. I could tell he was confused and didn't know what to do when I switched to southpaw. Then he tried switching to orthodox while I was southpaw, and I quickly switched back to orthodox and landed some more jabs and combos fairly easily. I'm pretty sure the only reason I was more successful when switching to southpaw is because he has less experience sparring than I do, but I felt comfortable switching back and forth. Don't think I had any issues with footwork or being off balance or anything like that. I could be wrong though. I've never trained in the southpaw stance when shadowboxing or hitting he heavy bag, but certain things I'm more comfortable doing left handed than right handed. Not sure if I should continue trying southpaw against southpaw and see how I do, or if I'd get destroyed trying to go southpaw against a more experienced southpaw.
A southpaw is usually going to have difficulty fighting an orthedox who converts. When you convert it becomes same stanced as opposed to cross stanced. The southpaw doesn't really know how to fight with the angles closed.