Originally Posted by
Kontact
The total stack height has nothing to do with it. Lower stack is generally very uniform with only the top half varying.
There would not normally be any reason to reduce the bottom of a head tube.
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.