998 or 1275 aren’t the only options, have you considered sourcing a 1098 crank, extra capacity = extra torque.
295 head, stage 1 kit, cam change could be a great engine
As well as the 1098 crank you'd need either 1098 pistons or the 998 pistons shortened on the crown, provided the crown is thick enough. If you over bore you can achieve around 1170cc and the long stroke will give very good torque.