The Virginia land grants and patents are digitized at the Library of Virginia. For a variety of reasons - penmanship, age, discoloration of paper - they are almost impossible to read. I trust Nugent’s transcripts. I haven’t found discrepancies in the ones I’ve managed to decipher. My experience with 17th century records is that names are spelled pretty randomly - sometimes there are differences in a single document.
Greer used the same records.