MT 6" Kurt vise with a swivel base weighs 115#. Are you sure of that weight?
To tell the truth,you are subjecting your mill to way too much weight,and it will cause the ways to wear out a lot more quickly. If you can find a 6" vise,I'd encourage you to do so. The vise is also twisting the table down from the front with so much hanging out like it is.
It's your decision,but a lot of trouble if your mill gets worn. I don't even move my table unless I first pump the oiling system till oil oozes out from the ways under the table.
Also,many leave their vise in the center of the table all the time. This wears out the lead screw in the middle. It is best to move the vise around some.