Yes, the 12"/45 Mk 5/6, and 12"/50 Mk7 (mounted on the Connecticut and Wyoming classes, respectively) were dramatically different from the 12"/35 Mk 1/2 mounted on the Texas and Iowa classes. The penetration and range values were very different due to the shorter length of the barrel, the efficiency of the propellant (due to the advances in propellant technology from the 1890's to WWI) and the design of the shells. Plus the rate of fire was much different due to advances in fire control doctrine (and would become even moreso with the widespread adoption of director fire control). Finally, the values for the USN in the FAI Supplement reflect the situation in 1917 (when the US entered WWI). As such, these values may not be valid even 5 years prior, since the US had adopted many of the 'lessons learned' from the early years of the war prior to their involvement. So I really can't recommend using any of the values from FAI (for all the nations presented) for any period prior much further back than 1910 (and even that is debatable).
A true, historically valid variant would require a complete, bottom up effort (much as FAI required the same when backdating GQ3.3). A simple backdating using the existing values absolutely will not suffice.