On Monday, November 13, 2017 at 11:44:21 AM UTC-8, Bob La Londe wrote:
I've got a project that needs to be indexed to drill a bunch of holes...
I can clamp the two spindexers to the table with a lathe truing bar between
them...
No comes the problem. They will need to be re-indexed to the machine every
time they are used

Ideally, you'd want those spindexers to have a bottom-mounted rib that engages
the mill table tee slot. If you add a reference surface (a button would do),
you can align 'em on the slot, and measure the button-to-button distance to space 'em.

I wouldn't involve the vise. You'll fiddle with its jaws some day.