These trusses are usually "crowned" on-purpose. You install with the crown up and then when they deflect they are flat. Maybe they put some upside down and some not. 3/4" sounds like too much crown. If they were originally crowned 3/8" and some were put in upside down then you might see a 3/4" difference. Can't quite tell from your terse descriptions - give us more to go on... If they were built with a 3/4" crown then maybe they were built to warehouse specs. or something, where they expected more load on them. Don't cut them - but if you couldn't help yourself, then remember it isn't the sides that stops the bottom chord from bending - the bottom chord is in TENSION, i.e. it is being PULLED end to end. If you cut it and then expected to repair it, you would have a gap, because to fall it would have to pull apart b/c it is in tension. I wouldn't want to try to repair it after this b/c it is acting as one member, end-to-end.