I'm just a little bigger than you, 5'8", 230 lbs, large calves, MP29 boot. I think one should look at markedly different things for a bc boot vs DH boot. If you are truly going bc and not sidecountry, light weight, large cuff rotation, and tech fittings are the best. Given a narrow foot, you might look for out-of-production TLT5, the Mountain version if you just want to tour around, the Performance version if you want to do fast, steep, deep, and or hucking. These are 2-buckle boots. The TLT 6 has a little wider last. The Scarpa Masestraele and SM RS are also good and fairly narrow. My stepson prefers the La Sportiva Spectre over the Dynafits for fits (i'm not sure why). I switched from 4 buckle Dynafit Zzero PU (a really nice, not too heavy boot, you still might be able to find somewhere), to 3-buckle Zzero Pbax, to the 2 buckle TLT5 (a little narrow for me) and then TLT6, nice fit for me, plenty of calf room but the mountain version is softer than the TLT5 mountain and I would go with the Performance. These are light weight boots, with removable tongues (the 6 has soft and stiff tongues). If you are really touring, not having to deal with extra buckles or power strap (I carry a Booster Strap in the pack), having a 40+ degree cuff rotation, and no forward resistance from an tongue make for more efficient longer strides, lower weight, and faster climbing speeds. If you think you must have more buckles, the Scarpa Masestraele and M RS are fairly narrow lasted. The Dynafit Mercury is stiff and I find a little loose in the toe and a little cramped over the instep with the very stiff tongue in, I think I could have gone a size smaller; the Vulcan is perhaps the stiffest out there. I bought the Mercury to use with my stiff, long radius 98 mm (184 cm Volkl Nanuk), 106 mm (182 cm Dynafit Stoke) and 112 mm (178 cm Voile V8) waisted skis. I use the burly "alpine overlap" Dynafit Zzeus lift served with everything from 184 cm Kastle LX 92s to 188 cm Rossi S7s and 191 cm Moment Bibby Pros. Personally I wouldn't use the boot for the bc given its weight, 4 buckles, lack of cuff rotation, and inflexible liner. My TLT6s work fine with my 182 Dynafit Cho Oyus (89 waist), 180 Voile Vectors (98 waist), and 177 Movement Shifts (135 mm shovel, 98 waist).
So if you are going with a light-weight pliant ski (the latter ones listed above) a 2-buckle boot is fine; if you are going to use a heavier, stiffer, more demanding ski then by all means consider a 3- to 4-buckle boot. I have friends that really rip, really ski the steeps, and ski off summits and use 2 buckle boots.
I have Plum Yaks on my Voile V8s and used them lift-served and bc with truly deep snow. I have had, and I detest frame binding for AT. I use Plum Guides with the stomp plate on my Shifts and like them a lot. I have used a variety of Dynafit bindings, liking the Verticals the best (out of production), and sitll have 2 pair of Dynafit Speeds I am in the process of designing stomp plates for--stomp plates help keep ice from building up under the heel while touring. If I were to buy a new pair of Dynafit bindins I'd buy the Speed Superlite and fit it with an adjustable B&D plate.
Edited by Andy Carey - 4/27/16 at 8:54am