BD Raven Pro or Raven Ultra

Rather go for a curved one, like Camp Corsa Nanotech (if should be light) or Petzl SumTec Adze (if it shall properly bit in blue ice as well)

Reason: more space for knuckles and more bite when holding the axe at the shaft below the head, when climbing up a couloir.

Since it’s only for splitboarding—of your two choices— I’d recommend the Ultra (but truthfully I recommend the Corsa Nanotech). I’m not sure what you gain with a 60 cm shaft over a 50 or 70. As I see it, this is not a split-the-difference and get both type of deal; either the spike hits the ground or it doesn’t.
Traditionally, shaft length should be determined by a combination of the distance from your hand to ankle (or floor) when standing upright and the terrain you’ll be walking in: the steeper the terrain, the more you’ll trim off that distance. I’m 6’0″; bigger blokes like you and me typically use +70cm axes for general-mountaineering. Since we splitboarders tend to use trekking poles on mellow terrain (anything less than 30º–35º), the traditional sizing method gives us shafts that are too long; and that’s just extra weight which makes self-arrests more difficult.
When I bought mine, I was thinking. . . I only use an axe in two situations: booting steeps (>35º) and self-arrests. That steep of a slope makes shaft length all but moot; in fact a longer shaft means I have to move my arm higher to get my spike into (and out of) the snow. In self-arrest scenarios, the spikes of longer shafts are more likely to hit something and go flying. Ergo, I should get the smallest, lightest axe I can afford.
But dudes on this forum rock very different lengths, materials, and styles. I have a feeling axes are a ‘you know what you want/need only after you’ve taken the plunge’ type deals. I hope to hear soon about how well your choice works for you.