That's about the same price I paid to have Spinmaster put together a DW set, a modified asian 7750 movement plus the exact mods you list (plus waterproofing, adjusting etc). Think the mods were then listed at additional cost $350. FYI, there are numerous suppliers of parts here (cartel stock from TDs, yuki, ingod44, NDT, phong etc - the latter more expensive, at least the phong case) - you better ask for clarification before pulling the trigger.
Here's my Spin 6263 (pardon the angle that makes the crystal look funny and the fact that I'm allergic to bracelets):