You want to convert from Hydragas to a conventional set up?
There are a couple of options, There is the Suplex system from the UK (has a pretty crap reputation, serarch Suplex here on the forum and I doubt you'll find a kind word!)
And there is the Aussie system made by the MG Centre of Sydney ( I haven't heard any complaints, only good stuff)
As to legality here in Australia, that would depend on which state you're in, as they vary in their officishness, but if you were to ask Vic Roads you will get the standard answer for something they don't know the answer for and can't be arsed finding out from the cluless idiot on the phone / behind the counter, and that will be that you'll require an engineers certificate (at great hideous cost to you)
Now as there would be only a handfull of people at Vic Roads would know what a MGF is, and even less would know how they work, (The authorities in NSW would be similar and the other states would be even more ignorant) what you don't tell them won't worry them.....your call!
The same goes for the theiving scum insurance companies.......yet again your call.
You should check with the MG Centre of Sydney, they may suffuicent compliance paper work to keep your state registration authority happy (from what I hear the WA dept of transport are, particulary ignorant, never happy and nearly impossible to please, much the same goes for SA)
Mike Satur has developed a coilover set up, it looks choice! but I haven't heard any pros or cons, and the same issues as above would apply.
I believe he also came up with some shraeder valve inserts to regas the original spheres, he did weld in and non weld in versions..... with these you would face no legal issues and would keep the car original. You would still have to pump up the Hydragas fluid from time to time and now the nitrogen gas too.
