If you were using a 150 DE, or a 250/400 watt SE type, I would recommend Radiums. But since you are doing 175 watters, the Ushio is probably a decent choice for a whitish rendition.
Only other thing to consider is some folks like a 20K rendition on a Halide bulb, but I am not sure of any 20K 175 watt bulbs to recommend, since it has been at least 15 years since I used any type of 175 watt halide bulb.
Hamilton Technology makes a 20K 175 watt halide bulb, and they are probably OK in Rendition. Hamilton also makes several different Kelvin rated 175 watt halide bulbs. XM makes one as well. There is also a cheapo brand called Plusrite, and you can get and try one of theirs for cheap if you like. Some folks really like them.
http://www.hamiltontechnology.com/shop/?cat=44">http://www.hamiltontechnology.com/shop/?cat=44</a>
[IMG]http://www.aquacave.com/XM-175W-20000K-Metal-Halide-Bulb-Mogul-Base-P5449.aspx?gclid=CKyB_pS8u74CFWsS7AodSQgAag">http://www.aquacave.com/XM-175W-20000K-Metal-Halide-Bulb-Mogul-Base-P5449.aspx?gclid=CKyB_pS8u74CFWsS7AodSQgAag</a>
[IMG]http://www.elightbulbs.com/Plusrite-02402-MH175-T15-HOR-20K-2402-175-watt-Metal-Halide-Light-Bulb&source=GoogleBaseCSE?gclid=CMrm4su8u74CFTBk7AodbiwAWA">http://www.elightbulbs.com/Plusrite-02402-MH175-T15-HOR-20K-2402-175-watt-Metal-Halide-Light-Bulb&source=GoogleBaseCSE?gclid=CMrm4su8u74CFTBk7AodbiwAWA</a>