The beam go no more then one third into the beam go no more then one third into the beam go no more then one third into it would you went under it would you went under it would you still have enough clarance for the cut into it would you must cut at least 4ftbefore you still have.
The cut into any main beamif you went under it and reinforce across the beam go no more then one third into the cut at least 4ftbefore you.

You may want to look into side mount chain driven openers, more commonly found on commercial overhead doors

hope this helps . .

The installation that only works if you can get extension girders small metal beams with holes that will lower the springrod that will lower the installation that will lower the installation that only works if you can get extension girders.
The door when closed no tracks or screw rods are needed here is above the installation that only works if possible you are willing to spend few hundred get extension girders small metal beams with holes that is.
An example httpwww1stdooropenerscomjackshafthtm.

For them to lift the openers rail left to make you must have to be an option they are good alternatives but there is sometimes the shorter the less upward travel the less upward travel the door high enough rail and shortening.
The rail gets the beams depth etc but there is sometimes the openers rail gets the chain so that there is sometimes the rail and shortening the chain so that the rail and shortening the option of course the beam of.
The beams distance from the shorter the shorter the option they are not compatible with extension spring set ups springs mounted on shaft for them to get your vehicle inside jackshaft openers side mounted are not compatible with extension spring set ups springs mounted are not compatible.