Does she start, idle and rev up normally in no load situations? If so does she accelerate at partial and full pedal and run on level streches in a normal manner up to highway speed? Did you read the old plugs and if not do you still have them? Cat can certainly choke the engine, the fuel flow to the carb can starve the engine. If you can run a fuel pressure check that will eliminate the fuel pump as the culprit (although the pump is operating fuel flow may be below operating requirements) if fuel pressure to carb is sufficiant the carb could be at fault. Steep inclines can starve a carb, but I'm guessing your referring to small inclines. I had a B2 that would run fine and then cut out on hills and corners and that turned out to be a wiring harness grounding out on the firewall. Lots of other things possible, but if you start, idle and rev up under no load I would look at basics first...gotta breathe in and out, with ple.nty of fuel and properly timed spark. Got to rememer that camshaft valve train and timing chain are sometimes at fault. I wish I had a simple answer and it may be a simple problem, but diagnosis at a distance and sometimes on the spot, is really just a guess without doing the detective work.