The term RA originated in 67 with the d-port exhuast and continued till bout mid 68 when the RAII o-port exhuast heads came out. In 69 Pontiac made slight engine/head changes and changed the terms to RAIII(d-ports) and RAIV(o-ports) which continued thru 70. Every year both style of heads had different casting #'s. BTY, Pontiac never listed RAI's in 67 or 68 even though they had a 1st and 2nd design 67(closed chamber), and different casting starting in 68(open chamber). Just called them RA.
