I'm pretty sure if it was registered on Oahu, instead of the Big Island, your title would identify the vehicle as a "Cobra", MODEL year, 1965, year first sold 1965, and finally STRD-RPLC (street rod replica).
On the outter islands it was always legal to register a "kit car", "home built", "replica", "dune buggy", whatever term you want to use. Until just a few years ago there was NO WAY to legally register any of the above mentioned on Oahu. That previous law was based on the number of residents per Island, with Oahu exceeding the target limit of population numbers, therefore, no legal way to register. Most of us registered our cars on one of the other islands using "Aunties" address (and various other under the table methods) and then kept a low profile on Oahu before "we" got the law changed. Some folks simply walked in, said they had a 1965 Ford Cobra and got it registered straight up as that BEFORE the Oahu law was changed (lucky bastards).
So, on the other islands it was always a bit of a crap shoot as to how the model and year would be determined, there was nothing consistent. ROAS almost certainly means Roadster, a fitting description, I guess...
With the new Oahu law it was BASICALLY meant to describe the vehicle as to what it most closely resembled (Dune Buggy, Porsche (replica of course), Cobra, GT-40, etc) and then note it was a "Street Rod REPLICA". My ERA was originally an "ASE" out of California, an Assembled vehicle (this was before the SB-100 method of Calif registration). It was re-named "Cobra" when I registered it on Oahu, as were many others at that time. The original California VIN was retained and a new VIN decal was installed on the car by Hawaii. Pretty much we all got in line and immediatly registered our "Cobras" following the new law, so it was a mass filing kind of thing, which may account for the consistency of at least the early cars being registered. It may well have stayed "ASE" had I registered it on another island, like yours is still a ROAS. No doubt there just doing like they always have on the Big Island (and Maui and Kaui), whatever comes around, whatever they feel like calling it on any given day.
Previous to owning the ERA I had an Excalibur, which was a "real" car (DOT and Federally approved and all that) so it was easy to legally register on Oahu exactly as it was before in any other state, a 1994 Excalibur JAC 427, with original VIN, as per factory description.