The 7i83 might help.
store.mesanet.com/index.php?route=produc...83_88&product_id=122
(that can connect to the smart-serial expansion channel)
But you would need to also consider the position feedback part of the equation so something like the 7i48 might be better,
But the 7i48 is not really compatible with the 7i92. You would normally use:
7i92 + 7i77 (note that the 7i77 could also be connected to the header on the 7i76E)
Or
7i97
Or
7i93 + 7i48 (or 7i33TA)
(All assuming that you want to continue with Etthernet as the link, If not then the 5i24 PCI card + 7i48 is an option.)
There are two styles of Mesa cards, 50-pin (HD) and 25-pin (DB)
They both offer advantages and disadvantages. (50 pin have 24 IO pins per header + GND and DB25 have 17 + GND)
You need to decide which way to go fairly early in the process as the card selections are different but overlapping. (there is no Resolver interface for DB25, for example)
Both types support additional Smart-Serial cards connected via CAT5 cables.