Just a note that the EFIS itself does not output ARINC at all. The HS34 adds ARINC-429 to the mix, mostly for interfacing with the Garmin 430/530 line. It outputs the following labels, though we don't have any experience with Avidyne products, so we would not be able to comment on whether or not it would work in your application.
ARINC-429 Labels Transmitted by the HS34
100G : OBS Value
203: Pressure Alt
204: Baro Corrected Alt
210: True Airspeedt
211: Total Air Temperature
320: Magnetic Heading