Want Radial T/A's for 67 Valiant with SBP rallyes

My girlfriends 67 Valiant has a set of old 205/60R14's on it that need replacing. She really wants some Goodrich Radial T/A's on there. I didn't think they'd have the size (or anything close these days) but I was surprised to see that they have 205/70R14 and 215/60R14's. I don't know what diameter these rallyes are but the tires on it now don't look like they're ballooning out too much. Which one of those two sizes would you guys go with? It's just a driver with a slant six, so we're trying to keep gas mileage in mind. Although cosmetically, the wheels and tires as they sit, look very small and don't fill out the fender wells at all. I'm no tire expert at all so I figured I'd ask before ordering and possibly not being happy with them once they're mounted. Thanks!