In 1954 (and all other Advance-Design years), 6.00x16" tires were standard equipment on 1/2 ton trucks. These came from the factory on 16"x4.5 wheels in 1953-54. The 6.50x16" RPO wheels were 0.5" wider in 1954 (available in sets of four or just as a pair for the rear).
Many earlier (maybe 47-52) standard 1/2 ton 6.00x16 wheels had 4.00 rim section width, and the 6.50 wheel/tire option in those years had a 4.5 rim section width.
It looks like (from Coker's website):
4.0-5.0" rim section widths are recommended for 6.00x16 tires; and,
4.5-5.0" rim section widths are recommended for 6.50x16 tires.
So, it looks like a 6.50x16 tire should work fine if you have 4.5 rims (if you have 1953 or newer rims, you are OK).
What is the brand of 6.50x16 tire that NTB has available? The recommended rim widths should be available from NTB or on-line.