As a general rule of thumb, souring does not make a bad beer better. That said, if you have a free carboy for a period of months and the inclination to sour something, why not go for it?
Lacto doesn't like over 10 IBUs, so your better bet is probably to hit it with some Pedio + Brett (you'll want to pitch these together, as pedio can produce substantial diacytal along with lactic acid, but the brett will eat it up). I'd add some fermentables, too. Maybe a quarter to a half pound of maltodextrine and some simpler sugars.
Check http://www.themadfermentationist.com/ for a ton of info and notes on sour beers, too, if you haven't already.
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