Your half reactions are correct and you have identified cathode and anode correctly.
One small problem : Once you change the sign of Eo after reversing the reaction, it no more remains Eo. This is not the standard Eo as prescribed by IUPAC. Let's call this reaction potential 'R'. It's not the standard electrode potential, since the reduction reaction with which it was associated (by definition) has been changed to oxidation.
So, once you reverse the sign, you just add the values. You don't perform Ecathode - Eanode. This formula is valid only if you have with you the actual values of Ecathode and Eanode.
The advantage of these R's is that you don't have to follow any formula. You just add the R's to get the R for the net reaction.