Good thinking there
even if someone else thought of it before
Front disc - rear V-brake is a very common setup. Heck, even I did that. One thing thou. Consider putting some hydro disc brake up front. I know many guys here are sold out to avid mechs but mechanical brakes will never be as good as hydros. look for some Maguras, and if u saved enough $$$ on rear brake look for old XT set.