I have to disagree here. Almost all 200-4r trannys are cast with the universal housing, having both bolt patterns.
Everything else is spot on. Here are some links with 200-4r tech.
http://members.aol.com/powerrslid/thm2004r.html
http://www.drwtransmission.com/thm_200-4r.htm
http://www.vibratesoftware.com/html_...nsmissions.htm
http://www.gnttype.org/techarea/tran.../200rebld.html
http://www.transmissioncenter.net/200-4R.htm
http://www.transmissioncenter.net/Tr...asurements.htm
http://www.drwtransmission.com/trans_weights.htm
http://www.nastyz28.com/transid.html
As you'll see, the PG, 350, 200, and 200-4r all share the same overall length within 1/8". Also, I'm not sure about the PG, but the 350, 200, and 200-4r all share the same output shaft. Swapping between these three is incredibly easy, like you said, you just need to relocate the crossmember and possibly change the mount for a different bolt mounting.