Hi J1125r, congrats on the fastback and good luck with it! I agree about that original color scheme of silver with orange but I remember reading that the Earl's Court show-goers were less than enthusiastic since they could imagine what their well-worn riding gear would do to dirty up that orange seat in a big hurry. Anyway, a fastback is always a treat to look at.
My congrats also on having the wonderful good fortune, as others have also pointed out, of being able to work with your Dad on this (and other) projects! Even a more important item than the bike itself. I'll never forget doing that with my Dad many years ago working on my first bikes and such. Have fun and good luck!