yel914, IMO, you should absolutely cover those classics with fabric.

If not Koverall & dope, a great alternative is Worldtex from Horizon Hobbies. It already has heat-activated adhesive on it ( like plastic film) but goes around curves like silk, doesn't bubble or sag, and best of all, looks very similar to doped silk; though not as glossy. It comes in a fair number of colors, but the natural (see wing in pic) can be painted any color you like.