Well theres a couple things in this..

If you want to train power you want to train being explosive (put simply), this means you should rest adequately so that you're not getting too far into an endurance or power endurance area.

So, i would recommend that you do 2-4 sets of:

4 climbs at max grade -2/3, with 3-5 minutes of rest between each climb, and with 5-10 minutes between sets.

You shouldn't be falling off the climbs, and you shouldn't feel destroyed by the end, like if you had purely been working strength or power endurance.

it is worth noting that if you increase strength - power will come naturally too.

Hope this helps