Hi David
The original Stanley 750 chisels are very nice. I have a set I put together over several years, somewhat modified to meet my personal specs, but they are good high carbon steel .... indeed I prefer mine to a couple of sets of Bergs I have had over the years. As you know, the LN chisels are modelled on these, and Stanley attempted to grab something from their reputation by bringing out the lukewarm Sweetheart series.
As to value, the 1/8" chisel is very rare, and alone can command in like-new condition at least $500, I would expect this set to sell for at least double what it current.
On a train to London
Derek