All you need to do is put the strap button on the end of the guitar in a different place! I've done this on many guitars with odd shapes and it works GREAT! here: move the button (NOT the neck one) to back or edge of the guitar on the upper wing where it comes to kind-of a point. I don't have a firebird in front of me but this will almost definately work! If you have one or go to the store and hold one try this...hold the guitar from the neck strap button and end button, it feels like it wants to dip neck down,right? now try this,,,hold the neck button and pinch the upper wing body point, it should tilt into a more traditional playing position...it may work better if you put it on the back instead of the 'side' and move it in alittle so it doesn't push the neck too far from you making you stretch you left hand to get towards the nut, but rather hangs where it should . give it a try, it might or might not work but it's worked for me in the past!