definitly worth the effort and the $$$ the 600F series is much better than the 900F series
assuming that the 625F still has it's factory setup, you will need to;
switch it to multi point hydraulic and electrical connector
add Dial-A-Matic
and depending on your combine setup you may need a wedge kit

for your combine;
add feeder house hooks
add gauge and switch to cab

i just converted a 630F for a customer with a 9610 last week, most of our customers that still have their older machines have bought newer heads for them, we have converted a lot of machines

 

i really don't see a difference between a late model 930F and a 630F even under the covers...someone care to explain?

 

the 600F series heads don't have hardly anything in common with the 900F series except for the "F"

900's have a mechanical flex mechanism that is based on springs and how much force you put on them determines the down force,
600's are called "Hydraflex" and use hydraulic pressure to regulate down force

600's have a larger auger with deeper flighting
600's are "full width cut" meaning that a 630F will cut 30 feet, 900's weren't a 930F only cuts 29.5 feet

other differences include;
600's only drive from 1 side
600's come from the factory with single point electrical & hydraulic connection
you need feeder house hooks to pickup 600's
600's have an integral stone dam built into the cutterbar to prevent small rocks from getting into the head (available in high and low)
600's have a 4" epicyclic knife drive, elimintating the wobble box

and in my experiences, 600's are much easier to work on

 

how would this work if you were going to be running different heads throughout a season? IE: a 630F platform, and a late model (07) 893 cornhead?

Sounds like the hooks could become a problem?

I know the single point is easy to get around since we switched our cornhead over to the 9x00 style, hooks sound like they could be a hassle?

 

the feeder house hooks will pick up all JD heads, old and new, its the old "banana casting" that won't pick up a new head