Disc Brakes or Drum Brakes

Thanks for the thoughts. This will not be a full-on restoration. More of a street/show/around town car. Can I switch to 15" wheels now (thinking of something along the lines of 15x7 all the way around) and still make the disc brake swap later without having to buy all new wheels again? The car needs new tires now (it has been sitting awhile and the tires have dry rotted) and I believe it is still sitting on the stock rims (13's I believe). I hate to buy tires to fit the stockers when I do not plan to keep them on the car.