from what i have been told, lhd cars can be registered in wa without having to convert to rhd any more. i don't see any reason why you couldn't bring it here. give dpi a call, have a look at
www.dpi.wa.gov.au for info and numbers and tell them the mods of it and what the deal is. you may have to fill out some paperwork and get the car engineered before you put it over the pits. good luck and i hope it all goes well