Both of these (pitcher to hitter, and vice versa) should be rare, but they should be doable, with some success. Besides Ankiel and Wakefield, you've got:
Bobby Darwin was Dodger pitching prospect in the 1960's who turned into a 20-HR, starting OF for Minnesota for a few years in the 1970's.
Willie Smith was a good Tigers pitching prospect in the early 1960's...came up as a pitcher in 1963; got traded to the Angels who used him as BOTH a pitcher and an OF in 1964. After that he was an OF....mostly a backup and PH, but he had a ten-year career in that role.
Bill Kelso was a minor league catcher for the Angels, who converted to pitcher. Made it to the majors in 1967 with the Angels, traded to the Reds in 1968 where he joined Jim Maloney, Billy McCool, Wayne Simpson, Gary Nolan, Don Gullett, Mel Queen as pitchers who blew out their arms in Cincinnati. (Never studied it, but I think there must have been something in how they trained...or failed to train...their pitchers there in the 60's, early 70's.) And speaking of Mel Queen...
Mel Queen was an OF who made it to the majors in that role and converted to pitcher at the major league level. Had one good season as a starter, hurt his arm, did nothing for a couple of years, went to the Angels and had a couple of decent years as a reliever.
More recently...like a couple of weeks ago...the Phillies sent pitcher Joe Savery, their 2007 #1 draft pick as a pitcher, to the Florida Instructional League to learn to play 1b.