There is no C-41 process film that is "easy" to push or pull. Most pro labs can and will (for a price) supply push or pull processing, but it doesn't work anything like as well as with Tri-X (or any other B&W emulsion, for that matter). That said, consumer films like Max 400 are probably closer to what you want; I've seen excellent acutance and very good storage characteristics with the Max 400 I've used. Unfortunately, it's available only in 35 mm. If you must have the same film in 135 and 120, your only choices will be professional films, most of which are slightly less robust to storage conditions (though even those aren't that sensitive -- airport x-rays are more a problem than storage for a few weeks). For my own use, I very much like Portra 400 NC in 120, and would probably shoot that in 35 mm if I didn't find Max 400 so completely acceptable and much, much cheaper.