I use this one;
http://www.screwfix.com/p/forge-steel-workshop-vice-with-swivel-base-4/50231
the one you’ve linked to will be ok for holding the shock (although you could probably just clamp it in the two halves ot he bench you linked to if you made a suitably shaped bit of wood.
[edit] I like the swivel ont his as I have it mounted on the corenr of the bench and can use it either at right angles to wear I stand or inline with it and it swings out the way when not in use. For you the Irwin one could be fine as it won;t be permanenntly fixed anyway.
If you ever want to start bashign wheel bearings out of hope hubs or holding heavier stuff (like forks) at an angle to cut steerers etc you may find you get more ‘wobble’ from the one you’ve linked to as it’s not secured to the workbench.