Wow !
Do you have some sentimental attachment to this engine/frame, or is it a test/challenge of your persistence.
Or ....
We hope you are young and enthusiastic - this may take some time ?
Unless you come across a stash of parts, or a good basket case.
Being in the UK would probably help here too. ?
I built up such a bike, starting quite a while back - when parts were at least around, and fairly
inexpensive. And I think it probably cost me about triple what a whole bike would have been.
All the small bits cost the most, you just don't appreciate how it all adds up.
A lot of the stuff around now are rejects from other folks restos, so the quality may not be great either. ?
And you'll get used to buying bits that don't fit or don't belong, unless you have a complete bike to compare to.
Now what does that fit ?
https://i.ebayimg.com/images/g/0UEAAOSwPMpfr-79/s-l1600.jpgIf you are prepared to use say Kawasaki wheels and Maico handlebars etc, then it will go a lot quicker, and less $$/££/EE
P.S. Look at all these folks hunting for James parts - you'll need to get in ahead of them !
https://www.oldclassiccar.co.uk/bikeads_make/james.htmOddly, there is no Captain section ?
Finding a good basket case or even incomplete runner is always a good ploy...
Good Luck !!!
Tell us how it goes.