I recently purchased one of these very movements for my Gen 2 chrono from a guy on the bay. The only small issue was that the date wheel is white and not black like the original.
Before going down the e-bay route I called Seiko who informed that if I wanted a full service to the watch they would charge me £150 inc postage. Where as I paid £60 the NOS movement and £20 for it to be fitted and the only thing wrong with old movement is that the 24 hour sub dial had died .