Phatty, I wouldn't use the RC helmet, it's too Republic. Use the grey one if those are your only two choices.
I can't wait to see it finished.
I don't particularly like the chest piece from the joe figure that your using though... but that's just me, it just doesn't "feel" mando enough. of course if your trying to invent a whole new mando style then go for it, as I believe that is what you will accomplish.