I'm not sure I would rely on a small LCD screen to show much more than lighting and composition, and if it looks OK in colour it will be OK in BW.
Any decent colour image will convert well into BW, and the extra detail captured by colour will make a better BW print too. I don't think that there is much that Photoshop (or similar) will not be able to do.
In addition, as already mentioned it's much better to have an original colour image for experimenting on.