oh that is not a "variant font", that is standard federal spec Series A on the second one - just like intended up to 1970 or so. Those signs are older than the one or two I saw in NJ with the Series B font. And yes, NH is similar too - I saw a couple of 9/202 pairs, which I believe you documented, with the Series B font on the 202 and the white background on the state route 9 shields.
the 202s are much older than the 9s. I am still unsure when NH switched from the "boring square" to the white-background Old Man; I have seen white background Old Man as old as 1977 and as new as 1984, and who knows when they switched to the black-background Old Man. I just know in 1986 when I was a kid, I remember just white-background Old Man shields... neither the white squares nor the black-background Old Man style.
the 202/9 pairs have white-background 202s that were repainted, to have the black background, likely in 1981 when their corresponding Old Man 9 shields were installed. The white-background US shields I think date to the 1950s; at least, I know that the 1961 MUTCD demanded black-background US shields, in contrast to the white-background of the 1948 MUTCD.