this coil works very well:
Cosmo Part Number: 2786-0
Part Description: Standard round core bobbin
Quick-Ship Part?: No - Variable stock may be available. Please inquire.
Part Dimensions:
Core Diameter Flange Size Length Wall
Front Middle Rear
.251 .640 dia. .720 .040
No Middle Flange
one made for me by Curtis to 2.65 kohm dcr (the one that appears light blue) using the Cosmo bobbins:
this switch works very well too and it is cheap:
but modify it to look like this: