I received my 750R showa shock last week. from the online data at racetech, it looks like the spring rate on that shock should close enough for me and my 620 so I don't have to swap out springs. If it warms up in the garage, I'll mount it and take some pics. I also picked up an adjustable tie rod with the shock -- total was $80 on ebay. Shock has under 300 miles and looks all but brand new. Keep your fingers crossed.
By the way, the guys at Racetech also told me that they can rebuild anything that has a schrader (bicycle tire type) valve on it for gas charging. Can't tell if the stock sachs does or not. Either way, the Showa is a much better shock with compr and rebound adjustability - so its worth the swap to me. Once I ride it around for a bit to get a feel for the current set up, I'll probably send to racetech for revalving. They were very confident that they could put together a valve that would make the 748 shock a superior replacement for this bike. Knock on wood, but I think we've found a B+ shock for the newer monsters at the under $300 price point, fully rebuilt. not bad..
mike