I don't know of any surgeons in the area offhand, although someone else might be able to chime in.
A couple things to consider:
If she goes too small, it'll end up looking like someone put a couple scoops of ice cream on a board. Meaning, the intra-breast gap might look unnervingly unnatural. Based on her height/weight (very loose speculation), 350-550cc might work out if she already has ample breast tissue to work with, eg, D-cups. Which brings us to the next point.
If she's starting out with ample boobage, her breasts might be somewhat ptotic. That being the case, her surgeon might urge/insist/only proceed with the surgery if a lift is included in the package. Think of a lift as a reduction done without excising additional tissue. The lift/small implant combo is usually a good result if the woman's goal is "a perky large C / small D". Which I doubt is the goal you're going for.
Going back to her weight/height (let's ignore for the moment that she would like to lose weight): if she goes too small, it might not be enough to "balance her out", so to speak.
Let's shift the convo to saline vs silicone. While there are lots of successes with saline, let's face facts: silicone just has a winning viscosity. If you've ever held a silicone implant in your hand, the 'feel' will probably unnerve your brain for a moment. Like, it doesn't take much of a stretch to imagine "this feels like human tissue". Once you get past that, it then becomes a "holy shit, this stuff is AMAZING" moment.
That said, it's not for everyone. Nor is it suitable for all surgeries. For example, TUBA is right out. And not all surgeons are experienced/willing to implant silicone via transaxillary incision.
However, a silicone implant doesn't automatically mean a ginormous scar. A skilled surgeon can work with the amazing pliable properties of the silicone implant and stuff it through a narrow stricture (incision). This is obviously a question to be directed to the surgeon himself/herself. "Pics or it didn't happen" will be useful here (ie, ask to see examples from his/her own patients).
Even then, there are things which can be done to dramatically improve on the scar, once all the external healing is done. I can't speak for all surgeons, but at the surgical clinic where my wife got hers done, they noted that they can do cortisone injections and laser treatments for reducing the redness/puffiness of the scars. A nicely healed scar should be a fine line which blends in with the skin color. YMMV, depending on the natural skin color.
I could throw out a few more considerations, but will stop at this one: always play to a surgeon's strengths. If the surgeon always does the incision below the nipple, don't beg/implore/cajole him/her to do it inframammary/transaxillary, for example. If the surgeon always gets excellent results going over the muscle, he/she might be very reluctant doing it under the muscle, for example. Basically, if you aren't hearing things from the surgeon that you want, then find another surgeon. Note also that certain techniques (eg, inframammary vs periareolar incision) seems to vary by region in terms of preference/popularity, so you might need to travel to get what you want.