Hi John. Welcome to the forum.
I do have someone interested in this but I have a feeling he is not going to go ahead with the deal. I'm going to give him until the end of the week.
But to answer your questions. To have it professionally stove enameled you're looking at about £100. To have it powder coated I was quoted £35, which I did consider having done. Or you could get some nitromors and spray it with car paint. Personally I'd go the powder coat route I think.
Seatpost is 27.2mm, bottom bracket is English threaded and stem is standard. All parts are readily available some of which are in my parts bin
I'll pm you when I hear from the other guy for certain.