Sidewalk texture, material and look will vary greatly between region and even within the same town.
Same with gobble stone patters, size and textures. So, IMHO, if you want to be 100% accurate you are on a quest that will end poorly.
Another material you might look into is sculpting foam like "Balsafoam" but it is best sealed wiith resin or foam boards covered with epoxy putty and than carved.
Of course you could rely on period pictures, do your measurements, etc of those.but ,IMHO, your best bet will be those 1/35 Tamiya sheets of roads, etc.
Doubt that even a person that lived through that time-period could give you a 100% accurate answer.
HTH.
P.S.: Unless you got a picture that you are basing your Dio on, I would go with artistic licence and use what works best for you.
Heck, it works for Hollywood and they get it wrong 97% of the times.