Hi, the 1930-1940 FB frames which I referred to earlier did not resemble this frame in any way. The fork crown was a plain casting and the lugs were of simple outline and certainly did not have any fancy slotted cut-outs. As a precision engineering company, you can be pretty certain that the top tube as shown on this frame would have been of the correct length and brazed-in correctly. If you visit the "chainring tattoo project" on Google you will find the silhouette of the FB chainring.