Both are acceptable, and understandable. However, the second is most likely the best. In American history, there are some subtle differences. Why is tenses in this order?

Sentence B is purely future tense from reaching out, letting you know, and finding are all the same tense. In the 3D world, these three things are related, and are to occur in order on a scale of 1 to 3; we’ll reach out to you and then get back to you with what we find. The implication is that the finding is related to reaching out.

Sentence A, uses a different tense for the finding. What we have found uses the perfect tense (usually used for something finished or completed), in contrast to the future tense of the rest of the sentence. What can we see how we found someone’s something as a result of reaching out? The first is assumed unless the context dictates otherwise.