The holster was made by the George Lawrence Co. formerly of Portland OR. The companies roots go back to 1857, and ended in 1985.
The holster is the #120 model, also called the Keith model for Elmer Keith. The number 528 indicates it was made to fit an S&W K-frame revolver with 6" barrel, such as the K22 and K38 Masterpiece models.
The three-digit code (e.g. 528) to show which holster was to fit which gun, was introduced in 1963 and remained in use until production ended in 1985.
The #120 was a popular revolver holster, both Elmer Keith and Skeeter Skelton used and recommended it.
I can't comment on the belt or on value, though there is certainly collector interest in vintage gunleather. You might try this link for more information:
