If it is the same as my '67 250S ( and I remember it correctly) , the instrument panel is held in by a threaded stud that sticks out the back of the panel. The stud passes thru a metal bracket, or strap, that runs left to right. A large plastic "nut" or threaded knob, screws on the stud and pulls the panel to the bracket.

You "simply" have to work your hand up in the back and unscrew the nut. It helps if you slide the seat toward the rear and lay on the floor with your head in amoungst the pedals. Also helps to have a small hand and thin forearm.

If I remember correctly, once the nut is off you can push/pull the panel forward a few inches. Watch for the speedo cable (and possible oil pressure pipe?) and of course all the wiring.

Hope this helps,
Dennis