In the original manuscript, Oliver Cowdery almost always spelled the word heed as head. There are 10 extant occurrences of his spelling for heed in 𝓞, and all but one are incorrectly spelled as head (the correct spelling heed is found in 1 Nephi 16:3). But in copying the text into the printer’s manuscript, Oliver gave the correct spelling heed in nearly every case. Of his 23 instances in 𝓟 of heed, Oliver initially spelled only two cases of heed as head. In 1 Nephi 8:33, he mistakenly wrote beheld, which he immediately corrected to headed by supralinear insertion; then he crossed out headed and wrote the correct spelling heeded inline. And here in Alma 51:15, Oliver initially spelled heed correctly, but then he apparently decided that head (what he had written in the original manuscript) was actually right, so he overwrote the second e with an a.
Later, in the print shop, the 1830 compositor rejected the reading head; but instead of restoring the correct heed, he decided that Oliver Cowdery’s head was an error for read. Using his pencil, the compositor overwrote the h of head with an r, with the result that he set read when he came to setting the type for this passage. All the subsequent printed editions have continued with this incorrect reading (“desiring that he should read it”). One could argue that Moroni’s petition began with a statement to the effect “please read”, but of course this interpretation is wholly unnecessary. Moroni was simply requesting Parhoron to approve his request, which makes much better sense.
Summary: Restore the word heed in Alma 51:15 (“desiring that he should heed it”); here in 𝓞 the word heed was spelled head, Oliver Cowdery’s typical misspelling in 𝓞 for heed (but rarely in 𝓟).