DUI Drysuits (San Diego) and several others use McNett Aquaseal as the primary seam sealant. As a rule, most drysuits that glue the seams use some sort of urethane adhesive. The rest (or at least most of them) use some kind of heat-activated tape.
3/4" is not a big tear; I would thin the adhesive (if Aquaseal, use unthickened Cotol if you can find it; MEK if you can't) at about a 1:1 ratio (really thin) and try to work the stuff into the fabric. Glue in a reinforcing layer of some kind of material (not really critical what, as it will be encased in glue); when somewhat cured, use a thicker mix (say, 3 or 4 parts adhesive to 1 part solvent) and go over the patch again.
Repair should, if using Cotol as an accelerator, take about an hour or two to accomplish.