Don't do it. My friend has like a 4 inch Jardini, and he had a 3 inch needle nose. The Jardini and it fought to no end, which resulted in both the fish being in bad shape. He eventually ditched the gar. In my opinion, don't get ANY fish that will swim up to the Jardini's level. My friend's Jardini even fought with his datnoid.... which rarely swam up. So be selective... if anything I would get yourself a nice ray or a small RTC / TSN.
REMEMBER though, all fish have different temperaments so your jardini could be a bit less aggressive (although they are one of the more aggressive arowanas). Gamble if you got nothing to lose but remember the warnings!