12 Volt or 6 Volt? If you posted it I missed it. Does it run very smooth at Idle? Does it start easy? Inline 6 is a torque motor. Hills should not be an issue(unless you want to go fast). I Think the Points/Condenser bit has been covered. So time to look at other stuff. One step at a time. Does the Coil get hot? Just put your hand on it while it is running? Don't grab the connections, just take it's temperature. Hot coil is breaking down or has too much current running through it. 12 Volt systems need a ballast Resistor to control the current. 6 Volt systems do not. Check the Resistor if you have one(most go "open" but some have a bit of metal in the back and can short). No Resistor? Running 6 Volts? Check timing, and advance it if needed. This can make a big difference in off Idle torque. Some good Tech tips for setting timing with a Vacuum gauge. I know this stuff is basic, but easy to skip or forget. Timing good? Check the Vacuum advance for leaking(easy to do and only takes a moment) Vacuum advance good? Check the fuel pump output. After all of that, it might be a good time to check the valve lash. A Vale that won't close will rob a lot of power. The last, bit matters. Valves can be a bit noisy and still work just fine. Too tight and the engine will run, it just will not "work". let us know what you find.
