Hello,
Port Townsend Foundry (
http://www.porttownsendfoundry.com/rigging.htm) has 1x19 thimbles. You can use oversized ordinary thimbles, but it will be hard to find appropriate-sized turnbuckles that will accept them. Serving the wake of the thimble is in any event a very good idea with 1x19. Do you have a source for annealed 1x7 seizing wire?
Good on you for working at this!
Fair leads,
Brion Toss