From SP Technical Service Manual –First edition 10/01/1994 by Pete Wolfinger:
"Poppet: The adjustable downstream valve has had 5 major poppet changes. Regardless of the actual shape and size, they all perform the same function. The current poppets fit nearly all of the older model units. The only reservation to this universal compatibility is that many times the demand lever must also be changed when a new poppet is retrofitted into an older second stage."
BTW I've started a new thread on the importance of correct lever height. You might find it helpful
Scubapro Second Stage Lever Height
