I'm a firm believer in large wire for power handling. 'Too large' isn't going to hurt anything, where 'too small' certainly can/will.
I don't think 14 gauge wire is large enough for either of those radios, but that depends on how long of a run that will have to be. If both will be going into the same vehicle, why not combine the longer runs in to one, then branch off from a much shorter distance? It also provides a means of adding things later without an additional power run. So how large? As large as you can manage. I would consider 8 gauge as a minimum, but I would also be planning for a few of those 'extra' gadgets in the future. I'd much rather have too much than not enough. One way of guessing about the size of wire is to at least double the size of whatever size wire the radio comes with, if the run is a short one. I figure a short run is one of five feet or less. Doubling that size again for each additional five feet is a very good idea.
Is that 'over building'? A little bit, but not as much as you might think.
- 'Doc