HI Guys Wavesailer, surfer and paddle boarder getting wing gear together 77kg 5'10
Conditions looking to wing in are 8-15 knots , learn flat water but then would be mostly in ocean rather than bay or lake Wing 5.5ish is a 2140 s26 HA Nash or similar axis 1120 BSC suitable ..
The Naish 2140 HA foil on an 85cm mast sounds good to me.. I don't think 85 is too long to learn on.. Breaching will feel like going over the handlebars but you shouldn't breach as much as with a shorter mast.
Not sure if you are totally new to foiling but learning on a HA increases the challenge. Definitely can be done but a lower aspect foil will be much, much easier to learn on.