Big vise mounting

[Toolmaker51]

Pedestal or bench mounted, be sure stationary jaw is on a vertical plane to the edge of the clamping surface. Otherwise you restrict the vise capacity of length and trying to work the end of a bar or other stock. Below is link to other conditions of mounting vises.
Thread: Obliged to post; Mounting of bench vises.

Some reason link is inoperative, so...
Copy and paste
Thread: Obliged to post; Mounting of bench vises.

But Wow! THAT is a vise. I give up any one of my vices for a vise like that, Lol. The horn supporting moving jaw looks very serious.
I know you'll tear it down and renovate it some. Best trick I know is to count how much backlash there is between screw and jaw movement. Turn a spacer of equivalent thickness and add a coil spring; not too heavy, just enough to make the handle park at whatever angle you place it. It will hold it open when two hands are required to load the workpiece.