I personally wouldn't bother with trying to make up a 14k mile deficit for 75k. If you were going MVP -> Gold, I would probably recommend it, but Gold -> 75k isn't a big increase in value. Gold already gets you free changes, companion upgrades, and 4 upgrade vouchers.
I might spend $500 or so, but as mentioned earlier it'll probably be close to $2k. Are you going to get 2k worth of value from the bonus miles and the 4 extra upgrade codes?