1929 Hudson Valve replacement help please.

I have heard that there is a "special tool" to remove the valves in the F-Head, does anyone know where I might find one or if there are any modern day equivalents? At some point someone said that they had an extra for me but that was before I actually started digging into this old beast.... Also the how-tos and tips on what to look for/ do would be nice! Thanks. 

V/R Nic