In dealing with the awkwardness of the original subordinate clause in this verse, Joseph Smith replaced the conditional as if with that and then changed the past-tense subjunctive had to the present-tense indicative has. The resulting text says that Nephi was so full of the Spirit of God that his frame had no strength, which is not equivalent to saying that he was full of the Spirit so much that it was as if his frame had no strength. The use of “insomuch that” elsewhere in the text always implies that whatever follows actually happened, as in this nearby passage:
Summary: Restore the original conditional phraseology in 1 Nephi 17:47 (“insomuch as if my frame had no strength”); the original clause is hypothetical, while the edited one (“insomuch that my frame has no strength”) claims an actuality.