Has anyone ever poured these, and after the floor is built, drill the anchor points, into the cured concrete? I realize it's not easy to measure the sonotube foundation piers, and what if you set the anchors a bit off, in wet cement?
Two ways to deal with this that you might consider:
• Get an adjustable post base anchor. These allow for a bit of alignment after the concrete sets up.
• Attach the anchors, saddles or what-have-you to the beam or post and have it temporarily supported where it needs to be. Then pour the concrete.
I've always used the adjustable bases John mentioned with good fortune. If you have your building outline all staked out accuately you should be able to place the anchor bolts close enough to work within the adjustments the bases allow. And John's second point would work too as long as you can manuver the beams around okay.
In a code situation, they would require an engineers approval of the anchoring method if it was something uncommon quite likely. Epoxy anchors require special inspection and expansive anchors would likely have to be spec'd as to embedment and holding power etc. by the engineer.