These are great little sets, I have a total of seven sets that use this chassis.
Great to see another one being restored to working order, I have a spare 1807 LOPT, I was wondering if it could be used as a transplant for a LV20?
It appears there were two different cabinets fitted to the B18T, the difference is the speaker grilles are a square cutout or as in your set, routed out as four apertures.
The later LV20 actually has a wider cabinet than it's predecessor.
Mark