Purplehaze - your bottle's from 1953 through to 1958. The term "liqueur" was used by most blending houses for their blends from the 1920 through to the early 1960's and was just a descriptive term that was used to show quality, in all cases it was 100% pure Scotch whisky. By 1970 it was used as we now know it today to mean whisky with added flavours i.e. Clayva.
Blended Scotch Whisky is made from Single Malt and Single Grain whisky's, Grain neutral spirit is called either Vodka or [with flavourings] Gin and never used in blended whisky and so it is correct in calling itself Blended Scotch Whisky.
I don't know about bourbons but I though they were the same as Scotch whisky which does not age in bottle but can often pick up what's called "bottle flavour" so it would be very difficult to compare it with a current bottling.