Ulster, Utica, Camillus, Colonial (Colonial were inexpensive but quality knives and blades) Western (Western (Colorado mfg) pocketknives are not common. They were better known for their sheath hunting knives.) Schrade, Forrester, Uncle Henry, Old Timer, Sears (made by several companies, most may be Camillus made) Sears, Montgomery Wards, I'm drawing a blank on the big hardware chain based in MO. it wasn't ACE)
Depending on your budget, Böker
Tree Brand, Otter Messer, pretty much any made in Solingen knife, Several of the now defunct old Sheffield brands,
Jack Black
is better to give you the Sheffield brands to look for than I am. I get them mixed up.
SHARP (Kmart specific brand made by several companies), Buck 110/112 (during the time period you mention the Buck slipjoints were made by Schrade or Camillus. Schrade made have the Swenden (sp?) key construction. Camillus made have pinned construction.) A.G. Russell? (good knives, but I'm not sure how economical they are) NYKC and Hammer Brand from that period was owned by Imperial- Schrade. The NYKC produced by Schrade were all high-end knives. Some of the Hammer Brand are as well.
Imperial-Schrade did make Hammer Brand a .,. "discount" ... line to complement the shell construction Imperial's. The Imperial's with pinned construction as opposed to shell construction are equal in quality to the comparable Schrade knives.
FWIW the shell construction knives have the same high quality blades as the pinned construction knives, and are plenty tough, tho slightly more apt to develope blade wobble over years of use, as the pivot pin(s) are not supported as well as on the knives with real bolsters,
My understanding is the Queen/Queen City and Schatt & Morgan knives made between 1960 and 1990 are high quality.
Some - but not all - of the no name "USA" and "Made In The USA" "gas station special" knifes are excellent.
I would avoid anything from Frost and Master Cutlery made during that period (if any still exist), and everything with Celluloid covers.