IMHO servicing at Bob Riley for that 1675 is an overkill. You will be looking at additional 1.5k for service at watchmaker intl...
All your really is really servicing the movement and pressure test it.. Perhaps a nicer insert.
I wouldn't pay more than $4800 for a 70's GMT. If the dial is correct for the serial range, i wouldn't touch the dial and hands. They look nice as it is...just my opinion
Flex