I believe the panel in the 2a is the same as in a Ventus 2ax. I loaned a portable to one of our club members that has a Ventus 2ax and he was able to velcro in on the glare shield. It's sub-optimal though as it sticks up a bit and the antenna are too tall and can't stand straight up.
You have a few options that I'd consider. My partner in an ASW-20 bought a suction cup mount that clamps the flarm and he has it a bit closer to him than the panel.
You can stick it on the panel, some are doing that.
You can also buy the portable unit and an external display. The external display can be used in addition to the built in display. The small rectangular external display will let you get more creative with placement.
I haven't got my external display yet, but need to. My Duo has the portable unit on the back panel which leaves the front seat blind to where the target is at.
The flarm really work well though. I highly recommend adding one to your ship.
Morgan