K-Series certainly does fit, I think you need a Ford Type-9 gearbox for it, and a few tunnel modifications. As I recall there are a few companies specialising in the conversion.
edit - yup http://www.frontlinedevelopments.com/
@lae started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
K-Series certainly does fit, I think you need a Ford Type-9 gearbox for it, and a few tunnel modifications. As I recall there are a few companies specialising in the conversion.
edit - yup
http://www.frontlinedevelopments.com/