SJX426 

Congrats! A 720 is nearly on my list. I have a 760 waiting in the wings.

WRT the Helicomatic hub. I have one that came on the 610 I purchased. The freewheel is near perfect and is available. The problem is with the cones. They are pitted beyond use and are unobtainable. The race in the hub is fine and 3/16 balls are easily found. The issues is maintenance. You need to check them frequently. I don't have a history with them but my impression is to check them once a year, at least. Keeping them greased will prolong the life of the cones. Some will say that 3/16ths balls are not as good as 1/4 but there is a argument that there is more contact surface area with more smaller balls, resulting in greater load distribution and reduced force on the races and per ball. The problem is that they rotate more per revolution. So just keep them lubed if the cones look good. If the cones are showing pitting. Start searching for a replacement hub. You will not find cones.

Being who I am, I would not go with changes except as needed. The exception for consideration is the RD. Don't fix what ain't broke. And if you do make changes, be sure you can undo them. I would be one of the ones screaming about spreading the rear triangles, especially if there is lots of room for a 7 block.

Above all enjoy!