I was about to do just the opposite: sell my 77 jazz and buy a Sadowsky.
I may be mistaken but don't the pot codes on your photos say 13th week of the year 77? If that's the case then it's impossible that the bass had come out of the factory in 1976.
My bass is similar. It's a 76 according to the serial number but the pot codes say 77. Mine has a four bolt neck.
I hear ya, I was about to order a NYC after selling my Merto, but the pots are 76. The 137 is for the manufacture CTS, next 2 number are the year "76" the next 2 for the week 18. CBS had a stock pile of pots in 1966 that lasted almost 10 years. They ran out in 75-76 and this would be the first run of new pots on this bass.
when it encounters such anomalies.