And my tuppence worth.
A pair bought new in 1964 should comprise a 3-6-9-12 Mastertime and an early 3-button Monte Carlo.
In the U.K., in good condition and depending upon the 'provenance', with an original backplate, box , guarantee and original receipt, these should fetch the high end of a Rally Master pair, maybe £2750 upwards ($4500),
probably more if they were a 'factory pair' or had a proven connection to a celebrity race or rally driver. Depending upon your location, you can get good info. about reliable watchmakers and insured shipping from this forum
BTW. You cannot do better than get advice from Jeff and Scott. If possible, we would all like to see your photo of them.
BR
David