Another vote for don't do it.
My Gradfather made me write right handed also. In Soccer I kick mostly left legged because it is stronger but am able to kick well right footed. I play Golf Right Handed and suck. I throw left handed and throwing a baseball is sometimes eratic and I throw a terrible spiral. My Handwriting is terrible. I have often wondered if all of this is because I was meant to be left handed.
About 10 years ago I made a resolution to convert myself to writing left handed. That lasted about two days.