A dynamo bracket is a really nice thing to have, if you ride at night. I'd put a dynamo on it!
I would not buy new parts for this bike; but try to pick up better used parts. You should be able to pick up a pair of wheels with aluminum rims, and a Suntour derailleur or two, pretty cheap; and this will make that bike much more fun to ride.
Indeed, I was not going to buy new: haven't done for months! Probabaly will find some good metal stuff from the period rather than the plastic simplex which I really dislike and do not understand how to adjust.
I may try and find some chrome mudguards, which i reckon would suit it pretty well, along with the lights.