What is the value of a c1970/1971 Autavia 2446C black dial three register (white) tachymeter with red second hand? Watch has a new back and bezel and checks out against the catalogue pictures for that year. New Heuer leather strap (matches catalogue) as well. Recently refurbished and runs great. I am being offered the watch from a friend/collector who had the work done on it.

Thanks for your help!