If you're happy to spend the time/money then SI rego would be well worth it, it would make things so much easier. If I were you I'd start making enquiries about getting a mod plate first, as Toffy said, because without that you won't get any sort of rego. Someone already mentioned Stephen Caplice, he did the report for mine for the RB25, he would probably be able to give you some more info. on getting the SI rego as well.