Cool frame. If the top tube isn't noticeably bent where that paint is flaking I wouldn't be worried about commuting on it. I think replacing the brake levers with modern hooded brake levers will be the best bang for your buck upgrade. Hooded levers and a new wrap of bar tape will make riding so much more comfortable than it is now, probably a bit safer too as you can operate them with more power from more hand positions. Not sure how much $ you want to put into it right off the jump but personally I'd switch the stem shifters to bar end shifters. Partially an aesthetic thing, but they are probably also safer and easier to use. If it were me I'd replace the cranks with something silver and square taper. Definitely an aesthetic thing, but the modern crank and BB are quite stiff and probably flex the heck out of that frame if you hammer on it. A square taper BB has a little give to it and would just feel more natural to me. I'm also quite partial to front racks, if you were planning to carry much weight on it I'd look into front rack options. I'm curious about that frame, is there a brand on the downtube or head badge / any stickers on the tubes near the BB cluster?