I have a Carrier 8000 58ZAV115-16 with a 1/2 hp 10.1 amp 3-speed blower motor sitting on one end of a long skinny house that needs more heat on the other end. I do not want to zone and believe the long insulated plenum that feeds everything could handle more air pressure. I would appreciate your input in considering replacing this motor with the 3/4 hp <slightly higher> amp motor. Is this do-able? What should I know? Many thanks.

Your system is a 115000 BTU that moves 1600 cfm of air. Was it sized for your home? You need to check to make sure the duct work is sized right. Did it cool your home with no problems?