Moe Norman used an overlapping grip when he played competitive golf.
The "baseball/palm grip" was promoted originally by Jack Kuykendall who founded Natural Golf Corporation. Mr. Kuykendall took a "scientific" approach to the golf swing and found that Moe approximated what he perceived to be the "optimum" way to hit a golf ball.
Moe was "used" to promote the Natural Golf way to play. Mr. Kuykendall is no longer with Natural Golf.
Moe was a "Single Axis" player . . . and a remarkable ball striker. Moe's protege, Todd Graves, continues to teach Moe's swing . . . primarily an overlapping grip.
For more information, use this hyperlink:
Graves Golf Academy