what you've done is very impressive and if you read what I had above I basically suggested this. But still does not make your watch a chronometer.
Wikipedia below lists the Swiss chronometer standards. As I stated above I am not sure that the general run-of-the-mill Seiko has a chronometer grade hairspring and or balance wheel. For instance if you look at ETA's manufacturing sheets for watches they'll list the specifications of the different grades. As soon as you go to the better or chronometer grade it's a different hairspring and balance wheel. conceivably than you may have a tough time passing timing specifications at the extreme temperatures that chronometers are supposed to run at.
what would be a fun test now is to pretend this is a Rolex and time it the way Rolex does. I'll have to get you a worksheet to fill out. The only catch is Rolex does not time at different temperatures so conceivably you could pass or equal a Rolex at least at room temperature.
then I didn't read every single technical word but in the past it was sad in that the only watches that can get Swiss chronometer status are Swiss watches. I think they've excluded other countries probably because they didn't want to look bad. To understand this look up what a grand Seiko is a beautiful timepiece that keeps beautiful time unfortunately does not have a beautiful affordable price like typical Seiko's would.
@CaptCalvin - I don't have a spare movement on hand, I was looking at buying a 25 jewel out of a Montblanc Meisterstuck which seem to be plentiful and relatively cheap. Here is an example with some photos.
@Bauertime - I will do some reading on addressing the hairspring, if it's a single part that needs to be addressed I can give it a go, but the watch has unknown service history so I'm not sure how worn the remainder of the movement is.
@bjd1020 - Thanks for the help! Yes, the concern is the blank space in the day slot. Is there a great deal of variance in movement sizes between 7750s that lack additional complications?