Hi, I am helping a friend on his 1956 T Bird.  He just bought it.  It had been sitting for 20 plus years.  I removed the gas tank and cleaned it and the gas lines, replaced fuel pump.  Installed new plugs and wires.  The disturber and carburetor were sent out for rebuild.  I replaced the heat tube in the intake. I checked the compression and it is 155 to 145 with one cylinder at 120lbs. . The radiator and water pump and hoses have been done. When the engine is running it sounds good.  It revs up good, but when you put it in gear (auto trans) it will barely move out of the garage.  I don't know what else to do.  Do you think that the one cylinder with compression at 120 is doing it.  No smoke or bad sounds.  Thanks for you help