You're completly right, that was what I consider my first option.
Just didn't know the word shimming.
Made a search around the net and found some usefull tips.
Even in the site of 'ender that I quote :
"Shimming is a procedure used to adjust the pitch of the neck in relation to the body. A shim
is placed in the neck pocket, underneath the butt end of the neck. On many American
series guitars, a Micro-Tilt adjustment is offered. It replaces the need for a shim by using a
hex screw against a plate installed in the butt end of the neck. The need to adjust the pitch
(raising the butt end of the neck in the pocket, thereby pitching the neck back) of the neck
occurs in situations where the string height is high and the action adjustment is as low as
the adjustment will allow.
To properly shim a neck, the neck must be removed from the neck pocket of the body. A
shim approximately 1/4" (6.4 mm) wide by 1 3/4" (44.5 mm) long by .010" (0.25 mm) thick
will allow you to raise the action approximately 1/32" (0.8 mm). For guitars with the Micro-
Tilt adjustment, loosen the two neck screws on both sides of the adjustment access hole on
the neckplate by at least four full turns. Tightening the hex adjustment screw with an 1/8"
hex wrench approximately 1/4 turn will allow you to raise the action approximately 1/32".
Re-tighten the neck screws when the adjustment is complete. The pitch of the neck on your
guitar has been preset at the factory and in most cases will not need to be adjusted."
Mite be of interest to someone else.
Probably will follow WezV tip and make a wooden shim once I found the rigth angle, still making some tests with a foild business card.
thaks