I use 175mm/170mm cranks on my 56x53cm Santana road tandem because I am generally the more experienced rider as the captain, and the 175mm captain cranks help to remind me not to go into a 130+rpm spin with a less experienced rider on the back, and the 170mm stoker cranks will help them to keep up if I do. I've done the same thing on all of my tandems, but on the mountain tandems I usually went with 180mm/175mm or 175mm/170mm cranks so that I would have the extra leverage when we needed it because I (thus we) often stand on steeper climbs or on more technical trails, but I don't want my stoker feeling like they are walking on a treadclimber.

I don't know what will work best for you, but for me, height and leg length are only part of what should be considered when selecting crankarm lengths on a tandem. On a tandem you ride as a team, and each rider's needs and abilities should be taken into account.