There were many Cobra kits of varying qualities back in the 80's and into the 90's run by guy's thinking they could make it big by becoming Cobra kit suppliers, but did not survive and only built a hand full of bodies or incomplete kits. This led to more brands than most people realise. This was in the day when using modified proprietry chassis was common, ie 356's on cut Bettle chassis, Pervis Eureka's on Beetles, Corvette replica on HQ ute chassis, and cobra's on Crown chassis. This is the way the kit car industry developed. We still build with coprimise by adapting best we can, proprietry suspension components because the cost to engineer and approve these bits is prohibitive to most.
This kit looks bad because it an amalgamation of new and old structures and what appears to be backyard welding and finish quality. And what also looks like another 20 years of road patina. Doesn't mean it's a death trap but certainly may struggle to meet today's more stringent requirements. Whether a lot of TLC is worth it, is up to someone like Enkleman's to advise. WA seems more leanient in the registration of this type of aproach.
This IS a Crown chassis, and is not modified in the traditional way. It was not common to add the steel framing in the engine bay with steel footboxes. Having said that, as i said previously there were many aspiring suppliers, and I have not seen them all, though I have seen many. The way the chassis has been modified is not the way G-Force did it. It was common, however, for the builder to modify one themselves.
There are differences with all kit suppliers bodies that can help identify them, however it is difficult from those photo's alone. You could buy a body only from most any supplier, but some the ones I recall to be either associated with Crown's or more obscure kit's that didn't make it so there were spare bodies available were; starting with the obvious, G-Force, Autostyling, GT Fibreglass, then Silhouette, Boomerang, Lucas, and Irrisistable Replica. Guy's could have also picked up a body only from WE Sports cars (Wooley & Evans) or Classic Glass. These were all mostly based in WA or SA.
I haven't got enough to tell you what it is, but can tell you it's not a G-Force or RMC. Reasons for this, front indicators are not on raised body mouldings, engine bay opening has different edge profile, and larger more bulbous front wheel flare. Some of these features also lead me to believe it is not WE or Classic Glass either. I have only seen one Irrisistable and Silhouette, a hand full of Autostyling's, and have not seen a Boomerang, Lucas or GT Fibreglass in the flesh, however have seen pic's. From all this i'm thinking an Autostyling or Boomerang fits the closest for the guard flare size and no indicator body mounts. Also the edge around the cockpit opening on most are rolled or radiused. G-Force has a larger radius, around 25-30 mm, RMC and I 'm sure WE and Classic have a smaller radius, around 15-20mm. Another identifier can be the head light mounting surface, some use a bezel from a Mini, which is a larger outer radius than MG which is more common/correct. This car seems to have MGB on its right and Mini on left.
Some areas you could look at are;
Inner door skin moulded profile,
This one is Lucas
Cockpit rolled edge size
Again Lucas like G-Force size;
Front flare size and shape
2 Autostylings;
front of door opening shape at return toward dash
Raised indicator mount (courtesy Lobelly)
RMC, G-Force and most newer kits
General Pic's;
Boomerangs - also looks simmilar to the Irrisistable
-note no raised indicator mount
Like Lobelly says, have a trawl through the Australian club web sites for pic's or Aussie ownwers pic's on this site. best way is click on the camera icon under their user name in a post. There are plenty of build shots from many angles.
There are many clues which help ID the body, but it helps to have a few around you to play comparies.
Good luck