Flatwound strings for sale back in early 1970's

La Bella
Fender (latest version with a new formula no longer offered in short scale)
Pyramid

 

La Bella Deep Talkin' Flat Wound Bass Strings - 4 String Set

PYRAMID Strings Gold Flatwound Short Scale Bass Strings - 4 String Set

 

fender 850 or f-80
labella 760m
pyramid gold
rotosound monel
optima rb
ghs precision flats

 

Generally, the LaBella short scale flats would be closest, as LaBella are the most "neutral" of the current flatwound production, and they have been in business making essentially the same string since the beginning of electric basses. The problem is that what we think of as the almost "woody" tone with a pick from many '60's and early '70's "Wrecking Crew" recordings with Carol Kaye was from Fender stock flats, and they just don't exist anymore unless you find a used set or an old stash.

Another option is that Optima is supposedly making a flat that is a reincarnation of the old "Maxima" flats that were also used by many, and were OEM on Rickenbacker basses of the era, including Macca tone. Again, the tone clips I have heard are very close, but not identical.