If you can do it in a BE95 travelair I'd recommend it. It covers the Be55 endo and if you can get 55/58 time that will get you up to speed on 310s and Ac50's which are the types you're more than likely to fly in your first twin job. Consider a PA31 endo down the track, at over $600/hr dual (for a nav let alone a chief) you'd be mad to do your MECIR in one... Unless you're Rick Kelly.
The 95 is very forgiving but is a good intro into twins and the Baron. They're a lot cheaper than barons 310s or similar aircraft to hire but you end up with "3" endo's. The 95 is readily available in Melbourne and once you hold your MECIR you wont have any problems hiring a BE55, a 58 will need about 100ME CMD. Both the 95 and 55 are very capable aircraft, the 95 CAN carry 5pax at about 160KTAS but its a stretch the 55 does it easy and at about 175KTAS. These are reputable speeds for any GA piston machine and will teach you good engine management and approach planning.
Not sure if thats available to you but I hope that advice helps.
Good luck.