It's kindof amazing, but the OnePlus One will have slightly
thinner bezels than the Oppo Find 7a.
But if the Find 7a specs are any indication, it will be a long little doggie:
Oppo Find 7a 5.5"
152.6 x 75 x 9.2 mm (6.01 x 2.95 x 0.36 in)
The Lenovo Vibe Z is really short-looking for a 5.5" phone with capacitative buttons, checking in at 149.1mm/5.87" tall.
Lenovo Vibe Z 5.5"
149.1 x 77 x 7.9 mm (5.87 x 3.03 x 0.31 in)
Without capacitative buttons, the OnePlus One could be a few mm shorter, but not much, especially if it has stereo speakers which will take up some room. If they make their goal of fitting a 5.5" display into a 5.0" chassis, then it really shouldn't be taller than about 145mm/5.7" but it seems like just under 150mm/5.9" is more likely.
With an aluminum body a little bigger than the HTC One M8 and slightly larger batter, I don't see it weighing less than 165 g (5.82 oz) and probably closer to 170 g (6.0 oz).