Thank you very much!
The housing hole is pretty tight, it's bored to match the shield of screw. Everything is massive, in steel, not cast iron, and imho very well made.
Unluckily i'm not able (like the anvil) to find the name of builder, it can be an italian product, but internet lacks of info about old equipment

I'm thinking about the floor support for the blacksmith vise, I have a round hollow large disck ( about 16" ) that can be a good base, but i'm not sure about size, type of locking vise