I do remember that the paint stripe means something.
Got it -- 1949 1950 1951 Ford Chassis Parts catalogue.
8A 5310 -B spring front coil marked with white paint - except convertible coupe
8A 5310 -C spring front coil marked with 2 yellow or blue paint marks - convertible coupe
8A 5310 -D spring front coil marked with three yellow paint marks
These are listed for 1949 1950
But, I think that this is what you have:
1A 5310 -A spring front coil marked with yellow paint stripe - except convertible coupe & station wagon 1951
They dont give measurements.
Page 43 of the catalogue