What type of license will allow me to modify a base font with original ligatures and resell it as a commercial icon font?

What licensing is appropriate for a font to be used as a base for an icon font?

So basically I need to use the UNICODE table of that font to include custom icons and sell that font.

Most of the free fonts out there are SIL, but I definitely don't want to include any license notice for the base font, since this is not the part of the font that gains attention. The icons are created by myself and will be included as a ligatures in the webfont.

For example. When the user hits a on the screen will appear a, which will be taken from the base font. But when the user types mail, the font will take this as ligature and display a mail icon.

The result will be similar to this one : Ligature Symbols