Compared to the power steering system you are taking out the cast iron manual box is still a weight loss. It is only a weight gain if you already had stock manual steering.

Lares lists new 16:1 boxes, I can only find the 24:1 boxes now. FF has rebuilt boxes, for more than the new Lares box.

Another options to think on, consider the Borgeson power box KIT Bergman sells, he's got it sorted and it is smaller than the stock power box, not sure how it compares size wise to the manual box.