Some queries - 1680 Red Sub

[bhall41]

I am new to the world of vintage Rolex. I am potentially interested to picking up a 1680 Red Sub (3.2 mil serial number) from a reputable dealer whom I know and trust.

Would it concern you or affect your purchasing decision if:

(a) the watch was running +8 seconds per day - should I get the watch checked out by a repairer before deciding whether to proceed, to see whether it is in good working order?

(b) the bracelet had, at some point, been replaced by a RSC with a 93510 bracelet with 593 end links ?

I have asked for the serial number. Is there anything else I should be especially wary about or make enquiries about? The watch comes with services papers from Rolex.

Many thanks in advance for your assistance.