Hi either she is an HA which are extremely rare. I remember way back in 1965 on journey home from a family holiday in Scotland , and at a refreshment stop seeing a brand new SL HA. So that was only in production a year and I am not sure when the 90s Deluxe and SL came out in either stock as per Deluxe or cooking Red painted high compression 90.
The HB was released in September 1966 and I remember being wowed by the gorgeous "Coke bottle " mini Chevy Camaro, shape of the two Vivas in The North Walsham Norfolk Dealership I expired en route home from School.
One an SL another a Deluxe.
I gathered as many brochures as the guys in the showroom would allow a 14 year old and they were considerably classy now artifacts( is that correct) brochures that said it all .
We got a new Pinewood Green Viva Deluxe 90 in June 67' and they went and changed the registration from E to F which was becoming a snob thing after folk started catching on to how to tell your motor was the latest.
Strange folk now covet 6 figure plates which many cars, particularly imported American one's were awarded as age related , and were often in allocated Scottish ones .
My very deadly now late Mother, ( who had a new Mini Austin 7 Mini in 1959) , out of all the nice cars she owned, albeit at nearly 98 couldn't quite remember the name, but seeing my Pampas Green one out of her care home window thought it was 'our old one' , the "green "Viva was always her favourite car.
Anyway if you have a 66 HB SL90 on a DPlate that is probably a rarity too.
Whatever, I think you have a car worth the effort Sometimes frustration and metaphorical 'blood sweat and tears' as they say.
I am in The Harwich Essex area if you need any help, or advice I may be able to assist you with anything please do not hesitate to ask.
Maybe we can see some pics, all in good time well done and
attached application form and letter explaining what you get 
