Originally Posted by
CliffordK
If the OP has sourced a fork with a steer tube that is marginally too short, then reducing the stack height by about 1cm may be enough to make it fit rather than shortening the head tube.
Depending on the head tube design, facers and reamers may do the trick, although they may not be designed to take down a lot of material. Perhaps first cut or grind it roughly to length, then face and ream it.
Removing material from the bottom of the head tube on a nice frame to make a too-short fork work is a terrible idea. This lowers the front end and makes steering steeper.