Like Clive says the Drives used play big part in how the current is handled. Also the Max voltage they can handle is important.
The motors will handle 70v no problem but you'll want 80V drives rather than 75v. This will give you plenty of safety margin and ensure the drives are not stressed or worse blown up thru back Emf.

So to answer your next question. The drives you want are Digital and the ones of choice are either Leadshine EM806 or AM882. Very little difference between them except the AM drives tend to be cheaper. The EM superceded the AM but in terms of performance there's not lot of difference. Em are slight smoother at lower speeds.