IMO a LNIB four inch 14-2 HB could bring $1500 to $2k,
A clean shooter grade gun would be a good buy around $600,

A HIGH condition gun with no box or docs probably somewhere in between.
Your serial points to the second batch from mid 1966,
Wondering if it has Diamond target stocks or Magnas ?
If Magnas are they non diamonds , flat bottom or PC curved style ?

Post some pics when you get a chance.