I think that will look very good!
Heated seats were not available when I bought mine, but if I did it today I would tick that box. A separate, plug in heater is less than ten pounds, though, so I manage anyhow.
Not sure about the louvres, but I would get the footwell storage box, the vintage catches, the rear mud guard and, by experience, the Blockleys. Definitely better than the Avons.
My "plastc" tonneau cover has ripped already, so I would go for the mohair one as well.
Understand fully that you want to get rid of the original steering wheel, as I have a Motolita.
Still debating if I should retrofit (two eared) spinners and tall roll hoops. No head rests, though.
If I had the possibility/ability to make my own exhaust I would not shell out for the Stage 1. There are so many choices of cool intakes on the market, or why not make one yourself, like I did? Start with standard equipment. Save that bit of cash!
Happy for you, man! You will have so much fun!