Thanks to Sheldon Brown's influence, I now have my own Raleigh Twenty converted to a fixed gear. A 53 tooth chainring mated to a 16 tooth cog with the 406 size wheels yields a comfortable 63 inch gear.
This Raleigh Twenty is a 1972 model - but the only parts I salvaged were the frame and seat tube clamp. It sports a black Rustoleum paint job of which Testors black is a dead match for touch up. Purchased a custom built fork built with a long steerer tube to get the handlebars higher (using a section of PVC pipe for the aheadset spacer - the "Tarik Device"). Other items are Suzue flipflop hubs, 36 spoke Sun CR-18 rims, 165 mm Sugino Mighty Tour crank, Roox 420 mm long seatpost, Brooks Pro saddle, Scott AT-3 bars with Cinelli cork tape, MKS platform pedals and Comet Primo 1.75 tires to soften the ride. Nimble steering, foldable to fit in the hatch of my Civic, and relatively light at 23 lbs - makes this project bike a major success. The Twentys are great bikes - see Asoka Mendis' bike # 381 on this list.
Thanks;Bill Milam, Maryville Tn.