Reading the info on the link you posted I don't see how it applies, or that you could even hope to get one. The car will not meet ADRs, that's the whole issue facing you, connverting to RHD is just one aspect. Many will have looked into this before you.
"A Letter of Compliance is a statement issued by a holder of an Identification Plate Approval (IPA). The letter will need to state that a vehicle complied with Australian Design Rules (ADRs) (other than the requirement to fit an identification plate) at the time the vehicle was first delivered for use in transport."